Abstract
Background:
Literacy, the ability to access, understand, and utilize information and concepts from diverse sources in ways that promote good outcomes is key to successful aging. Domain-specific health and financial literacy are particularly relevant to older adults as they face increasingly complex health and financial demands including those related to chronic conditions like type 2 diabetes. We therefore investigated the associations of literacy, including health and financial literacy, with diabetes indicators (i.e., hemoglobin A1c and blood glucose) in a community-based cohort study of aging.
Methods:
Participants were 908 non-demented older adults (age~81y;75%women) from the Rush Memory and Aging Project. Literacy was measured using questions designed to assess comprehension of health and financial information and concepts and yielded a total score and domain-specific health and financial literacy scores. Non-fasting hemoglobin A1c and blood glucose samples were collected, participants were queried about diabetes status, and medications for diabetes were visually inspected and coded. Participants also underwent a cognitive assessment, medical history, and depressive symptom screening.
Results:
In separate multivariable linear regression models, total (p-values≤0.03) and health (p-values≤0.009) literacy were inversely associated with hemoglobin A1c and blood glucose levels after adjusting for age, sex, education, hypertension, global cognitive functioning and depressive symptoms. Financial literacy was inversely associated with hemoglobin A1c levels in adjusted models (p=0.04). Sensitivity analyses conducted among individuals without diabetes revealed similar results.
Conclusion:
Lower literacy levels are associated with higher diabetes indicators, particularly hemoglobin A1c which is suggestive of longer-term glycemic instability. Further, these associations are independent of diabetes status.
Introduction
Literacy is a key determinant of independence and health across the lifespan but is increasingly important at older ages when individuals face increasingly complex medical and financial pressures. Health literacy, defined as the ability to access, understand, and utilize health information and concepts in ways that promote good health outcomes (1–3), is critical to navigating self-care and lifestyle modifications associated with chronic diseases commonly faced by older persons such as type 2 diabetes. Likewise, adequate financial literacy (3), which may be relevant to preventing cost-related nonadherence in high-risk groups such as individuals with diabetes and other chronic conditions (4). Approximately 10 million individuals ≥65 are currently diagnosed with diabetes and 48.3% of remaining individuals in this same age range have prediabetes, i.e., elevated levels of hemoglobin A1c or blood glucose (5). When combined with the fact that adults 65 and older display surprisingly low levels of health and financial literacy (6, 7), it is important to ascertain the relationship between literacy and diabetes indicators in older adults with and without diabetes and to determine whether such associations are independent of diabetes status.
Our group and others have investigated the relationship between literacy and various negative health outcomes. Lower levels of health and financial literacy are associated with less frequent participation in health promoting behaviors (1, 8), poorer decision making (3), greater cognitive decline (9), incident dementia (10) and mortality (11). Despite the fact that poor cognition is linked to lower health literacy in adults with diabetes (12), and that lower health literacy, and to a lesser extent financial literacy, have been associated with poorer self-management of diabetes (13) and nonadherence to glucose-lowering agents [for review(14)], no study, to our knowledge, has examined the association of literacy with hemoglobin A1c and blood glucose levels and determined whether these associations are independent of diabetes status. This is particularly important given that older adults without diabetes but with elevated levels of diabetes indicators may benefit from improvements in literacy and subsequently health promoting behaviors to reduce diabetes risk.
This study examines the associations between literacy, i.e., health, financial, and total literacy, and objectively measured diabetes indicators, i.e., hemoglobin A1c and blood glucose levels, in a community-dwelling cohort of older adults with and without diabetes. Based on previous studies in patients with diabetes (15–17), we hypothesize that lower levels of health, financial, and total literacy would be associated with elevated levels of hemoglobin A1c and blood glucose. Declines in cognition are seen with aging (18, 19) and diabetes (20, 21) and also contribute to lower literacy in older adults (2); however, our work suggests that literacy, regardless of type, is a relatively distinct construct influenced by but not equivalent to cognition. Thus, we further hypothesize that the associations between our three literacy measures and diabetes indicators will remain after controlling for age, global cognitive functioning and other relevant factors.
Methods
Participants
Individuals included in this research were participants from the Rush Memory and Aging Project (MAP; 1997-present), an ongoing longitudinal clinical-pathologic cohort study of aging (22, 23). The Institutional Review Board of Rush University Medical Center approved all studies and participants gave written informed consent in accordance with the Declaration of Helsinki. Participants were enrolled without known dementia and underwent annual clinical evaluations. Participants are asked to provide their Medicare Healthcare Insurance Claim number or social security number at the time of enrollment. Our most recent assessment of this information (April, 2018) revealed that 1,863 of the 1,929 MAP participants (96.57%) provided this information; thus, over 95% of our sample has health insurance in the form of Medicare.
MAP started in 1997 with an assessment of literacy introduced in 2010 (24). To date, 1,939 participants have enrolled and 1,921 have completed baseline evaluation including a cognitive evaluation. At the time of these analyses 1,146 participants were alive and active in MAP; of those, 1,056 had available literacy data. We excluded 62 participants who had dementia at the time of their literacy assessment (defined below). Of the remaining 994 participants, 908 (91%) participants had complete data on literacy and diabetes indicators.
Clinical Diagnosis
All participants underwent uniform structured clinical evaluations (23). The diagnosis of dementia was made by experienced clinicians and followed the National Institute of Neurologic and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association criteria (25). All participants in the current analyses were without dementia at the time of the literacy assessment.
Literacy Assessment
Literacy was assessed with 32 questions measuring knowledge of health and financial information and concepts, and numeracy (i.e., simple calculations) (1, 3). The health literacy component consisted of 9 questions assessing knowledge on leading causes of death in old age, the ability to follow prescription instructions, and understand drug risk and Medicare [e.g., Medicare Part D covers which of the following? (a) Inpatient hospital services, (b) Outpatient physician services, or (c) Prescription drug benefits’]. The financial literacy component consisted of 23 questions, many adapted from the Health and Retirement Survey. Financial literacy questions assessed knowledge of economic concepts [e.g., ‘A mutual fund is an investment that holds what? (a) Only stocks, (b) Only bonds, or (c) Stocks and bonds’] and ability to perform simple monetary calculation [e.g., ‘If a television set is on sale for $899, which is $200 off its normal price, what is the normal price? (a) $699, (b) $1,099, or (c) $1,299’]. Questions, either multiple choice or true/false, were scored as correct or incorrect, and expressed as the percent correct of all items (0–100%) calculated separately for health and financial literacy components. A composite score for total literacy was obtained by averaging health and financial literacy percentages. Total, health, and financial literacy scores have been shown to possess adequate psychometric properties (1, 3), and relate to many health behaviors (1, 9, 10).
Diabetes Indicators
Standard procedures were used to collect non-fasting blood samples. Phlebotomists and nurses skilled in venipuncture collected the blood specimen using sterile techniques. Specimens were then transferred to Quest Diagnostics for analyses. Tests important to this study involved a complete blood count for the quantification of hemoglobin A1c, expressed as a percentage of hemoglobin, and a basic metabolic panel which included a measurement of blood glucose (mg/dL). We investigated hemoglobin A1c and blood glucose given that each represents a distinct metric of blood sugar control: glucose for short- and hemoglobin A1c for long-term (i.e., 3-month) indicators of health.
Participants were queried about diabetes status and supplied all medications prescribed by a doctor, vitamins, supplements, and over-the-counter remedies/medicines taken in the 2 weeks prior to the study visit. Visual inspection of all containers allowed for medication documentation. Medications were coded using the Medi-Span Drug Data Base system (26) including prescription medications for diabetes (insulin and non-insulin related). An individual was deemed positive for diabetes based on self-reported diabetes and/or possessing prescription medications for diabetes.
Covariates
In addition to age, sex and years of education, we adjusted for variables outlined below. Given that over 95% of MAP participants are insured through Medicare, we did not adjust for insurance status or access to care.
Hypertension Status –
Given hypertension is present in ~70% of individuals with diabetes in the US (27), we included hypertension status as a covariate. Blood pressure (BP) was measured in the right arm with a mercury sphygmomanometer by trained research assistants (28). Two seated BP readings were taken at 30 second intervals following a 5-minute rest period; 1 minute after being requested to stand, a standing BP was taken. Systolic and diastolic BP was calculated separately by averaging all three readings. Hypertension was defined as systolic BP≥140 mmHg or diastolic BP≥90 mmHg or antihypertensive medication use (as outlined above). Individuals missing BP measurements (4.8% of the sample) were still coded if their antihypertensive medication use was documented (32 were on medication, 15 were not).
Global Cognitive Functioning –
All participants underwent an annual cognitive evaluation detailed elsewhere (2, 3, 22, 23). Briefly, cognitive tests were administered in an identical fashion at annual evaluations. A global composite score was created by converting raw scores on the 19 cognitive tests to standard (z) scores using the mean and standard deviation from the baseline evaluation. A person’s standard scores across all tests were then averaged to yield a single composite score summarizing level of global cognitive function.
Depressive Symptomatology –
Depressive symptoms were assessed with a 10-item version (29, 30) of the Center for Epidemiologic Studies of Depression scale (31). Participants were asked whether or not they experienced each of ten symptoms much of the time in the past week. The score reflected the total number of symptoms experienced (maximum=10).
Statistical Analyses
We tested bivariate associations between key participant characteristics and diabetes indicators, i.e., hemoglobin A1c and blood glucose levels, using correlations or independent sample t-tests as appropriate. We used linear regression models to examine the associations of literacy – total, health, and financial literacy (separately) – with diabetes indicators (separately for hemoglobin A1c and blood glucose). In these models, each diabetes indicator was the continuous outcome. All models included terms for age, sex, and education. Models were then repeated adding diabetes status (i.e., medication use and/or self-report of diabetes), hypertension status, global cognitive functioning, and depressive symptoms as covariates. We also performed a series of sensitivity analyses; e.g., we excluded individuals with self-reported diabetes and/or medication for diabetes to determine whether the relationship between literacy and diabetes indicators in older adults was independent of diabetes status. Analyses were programed using SAS/STAT software, Version 9.4 of the SAS System for Linux (SAS Institute, Cary, NC).
Results
Participants were just over 80 years on average, and the mean years of education was approximately 15. Over 90% of participants were non-Latino White and the majority were female. Mean literacy scores ranged from roughly 70% for total literacy to just above 60% for health literacy. Average hemoglobin A1c was 5.9% or 41 mmol/mol and average blood glucose was 102.4 mg/dL. Approximately 10% of our sample was taking medication for diabetes; an additional 2% self-reported diabetes but were not taking medications for it. Almost 80% of our sample met criteria for hypertension. Other covariates are described in Table 1.
Table 1.
Participant Characteristics, Diabetes Indicators, and Literacy
| Values | Range | |
|---|---|---|
| Participant Characteristics | ||
| Age (years) | 81.20±7.52 | 58.81 – 100.77 |
| Education (years) | 15.46 ±3.03 | 5 – 28 |
| Sex (female), n | 75.33%, n=684 | |
| Global Cognitive Functioning | 0.23±0.50 | −1.56 – 1.63 |
| Depressive Symptoms | 0.88±1.43 | 0 – 9 |
| Diabetes Indicators | ||
| Hemoglobin A1c (%) | 5.90±0.60 | 4.40 – 10.70 |
| (mmol/mol) | 41.00±6.6 | 25 – 93 |
| Glucose (mg/dL) | 102.44±33.41 | 44 – 345 |
| Literacy (%) | ||
| Total Literacy | 68.90±13.88 | 2.17 – 100.00 |
| Health Literacy | 63.27±17.68 | 0 – 100.00 |
| Financial Literacy | 74.52±15.31 | 4.34 – 100.00 |
Note: Data indicates mean±standard deviation unless otherwise noted. Total literacy is the average of health and financial literacy scores.
Bivariate correlations between key participant characteristics and diabetes indicators (Table 2) revealed that only hemoglobin A1c negatively correlated with education (p=0.002); neither hemoglobin A1c nor glucose correlated with age. Independent sample t-tests indicated that hemoglobin A1c levels did not differ by sex, but men (110.0±45.0 mg/dL) had higher glucose levels than women (100.0±28.2 mg/dL; p=0.002). All three literacy measures were negatively correlated with hemoglobin A1c (p-values≤0.003), while total and health literacy scores were negatively correlated with glucose (p-values≤0.01). Both diabetes indicators negatively correlated with global cognition and positively correlated with depressive symptoms (p-values≤0.03).
Table 2.
Correlation of Key Participant Characteristics and Diabetes Indicators
| Hemoglobin A1c (%) | Glucose (mg/dL) | |
|---|---|---|
| Age (years) | 0.02 (0.40) | 0.04 (0.22) |
| Education (years) | −0.10 (0.002) | −0.05 (0.13) |
| Global Cognitive Functioning | −0.11 (0.0009) | −0.09 (0.006) |
| Depressive Symptoms | 0.07 (0.02) | 0.07 (0.03) |
| Total Literacy | −0.13 (<0.0001) | −0.08 (0.01) |
| Health Literacy | −0.12 (0.0002) | −0.10 (0.003) |
| Financial Literacy | −0.09 (0.003) | −0.03 (0.30) |
| Glucose (mg/dL) | -- | 0.61 (<0.0001) |
Note: Values are Pearson correlation coefficient (p-value) with significance set at p<0.05.
Association of Literacy with Diabetes Indicators
We first examined the association of total literacy with indicators of diabetes. In a regression model adjusted for age, sex, and education, there was an inverse association of total literacy with hemoglobin A1c (p=0.0007). This association of lower literacy scores with higher levels of hemoglobin A1c remained after additional adjustments for diabetes status, hypertension status, global cognitive functioning, and depressive symptoms (specific estimates in Table 3). Likewise, in a regression model adjusted for age, sex, and education, there was an association of lower total literacy with higher blood glucose levels (p=0.01) that remained after additional adjustments for diabetes and hypertension status, global cognitive functioning, and depressive symptoms (Table 3).
Table 3.
Associations of Total Literacy with Diabetes Indicators
| Adjusted for: | Hemoglobin A1c (%) | Blood Glucose (mg/dL) | |||
|---|---|---|---|---|---|
| Core | Fully adjusted | Core | Fully adjusted | ||
| Age | −0.001 (0.002, p=0.57) | 0.001 (0.002, p=0.48) |
0.02 (0.15, p=0.88) | 0.19 (0.13, p=0.17) | |
| Sex | 0.12 (0.04, p=0.006) | 0.05 (0.03, p=0.12) | 11.77 (2.61, p=0.00001) | 8.16 (2.32, p=0.0004) | |
| Education | −0.01 (0.007, p=0.05) | 0.002 (0.005, p=0.63) | −0.47 (0.40, p=0.23) | 0.23 (0.35, p=0.50) | |
| Total Literacy | −0.005 (0.001, p=0.0007) | −0.005 (0.001, p=0.00008) | −0.21 (0.09, p=0.01) | −0.19 (0.09, p=0.03) | |
| Diabetes Status | 1.10 (0.04, p<0.00001) |
50.19 (3.01, p<0.00001) | |||
| Hypertension Status | 0.09 (0.04, p=0.02) |
0.19 (2.43, p=0.93) | |||
| Global Cognition | −0.01 (0.04, p=0.71) |
−1.45 (2.44, p=0.55) | |||
| Depressive Symptoms | −0.0003 (0.01, p=0.98) |
0.37 (0.68, p=0.58) | |||
Note: Values are unstandardized coefficient (SE, p-value) from linear regression models with significance set at p<0.05.
Next, we examined the association of health and financial literacy (separately) with diabetes indicators. In a regression model adjusted for age, sex, and education, there was an inverse association of health literacy (p=0.004) with hemoglobin A1c. This significant association of lower health literacy and higher hemoglobin A1c levels remained after adjustments for diabetes and hypertension status, global cognitive functioning, and depressive symptoms (specific estimates in Table 4). In a regression model adjusted for age, sex, and education, there was an inverse association of lower health literacy (p=0.03) with higher glucose levels that remained regardless of additional adjustments (Table 4).
Table 4.
Associations of Health Literacy with Diabetes Indicators
| Adjusted for: | Hemoglobin A1c (%) | Blood Glucose (mg/dL) | |||
|---|---|---|---|---|---|
| Core | Fully adjusted | Core | Fully adjusted | ||
| Age | −0.001 (0.002, p=0.72) | 0.001 (0.002, p=0.46) |
0.04 (0.15, p=0.78) | 0.18 (0.13, p=0.17) | |
| Sex | 0.09 (0.04, p=0.03) | 0.02 (0.03, p=0.57) | 10.51 (2.60, p=0.00006) | 6.83 (2.28, p=0.003) | |
| Education | −0.01 (0.006, p=0.01) | 0.001 (0.005, p=0.86) | −0.58 (0.38, p=0.12) | 0.20 (0.34, p=0.56) | |
| Health Literacy | −0.003 (0.001, p=0.004) | −0.004 (0.001, p=0.00007) | −0.14 (0.06, p=0.03) | −0.16 (0.06, p=0.009) | |
| Diabetes Status | 1.09 (0.04, p<0.00001) |
50.49 (3.01, p<0.00001) | |||
| Hypertension Status | 0.08 (0.04, p=0.03) |
0.08 (2.42, p=0.97) | |||
| Global Cognition | −0.03 (0.03, p=0.42) |
−1.60 (2.32, p=0.49) | |||
| Depressive Symptoms | 0.001 (0.01, p=0.90) |
0.43 (0.68, p=0.52) | |||
Note: Values are unstandardized coefficient (SE, p-value) from linear regression models with significance set at p<0.05.
There was an association of lower financial literacy (estimate = −0.004, SE = 0.001, p=0.005) with higher hemoglobin A1c levels after adjusting for age, sex, and education that remained after additional adjustments for diabetes and hypertension status, global cognitive functioning, and depressive symptoms (estimate = −0.002, SE = 0.001, p=0.04). The association of financial literacy with glucose was not significant regardless of adjustments.
Sensitivity analyses
To further examine the robustness of our findings, we conducted a series of sensitivity analyses. First, we excluded individuals who self-reported diabetes and/or were on medications for diabetes at the time of their evaluation (n=114) to determine whether our reported associations were independent of diabetes status but remained related to the spectrum of normal to preclinical levels of disease, i.e., prior to diagnosis or treatment. Without individuals with diabetes, the associations of lower total literacy with higher hemoglobin A1c and blood glucose levels were unchanged (p-values≤0.04). Likewise, the associations of lower health literacy with higher levels of these same diabetes indicators were also unchanged (p-values≤0.02). Analyses excluding individuals with diabetes revealed a similar association between lower financial literacy and higher hemoglobin A1c, however, the fully adjusted model was not significant (estimate = −0.001, SE = 0.001, p=0.12). Second, we investigated the association of literacy with diabetes status to help determine the explicit relationship of literacy to diabetes status in our sample. The associations of literacy – total, health, and financial literacy (separately) – with diabetes status were not significant regardless of adjustments (p-values≥0.12).
Discussion
We investigated the association of literacy with diabetes indicators in a community-based study of more than 900 non-demented older adults with and without diabetes, the majority of whom (~95%) had Medicare. Lower levels of literacy, particularly health literacy, were associated with higher levels of hemoglobin A1c and blood glucose. Lower levels of financial literacy were associated with higher levels of hemoglobin A1c. These findings were not driven by persons with self-reported diabetes and/or medications for diabetes. Results suggest an important link between literacy and diabetes indicators in old age, a link that is present among persons with elevated levels of diabetes indicators that may not come to the attention of the medical system for diabetes-related issues.
These results build upon the literature on literacy and diabetes in several ways. First, the majority of studies investigating the association of literacy, specifically health literacy, with diabetes indicators are conducted in patients with diabetes from primary care clinics (32, 33, 35) or community-based volunteers with diabetes (17, 36). In contrast, our study investigated the associations of literacy, health and financial literacy, with diabetes indicators in participants across the spectrum of normal, preclinical, and diabetic levels of hemoglobin A1c and blood glucose. Results suggest that lower levels of total and health literacy are associated with elevations in diabetes indicators. Second, sensitivity analyses excluding individuals with self-reported diabetes and/or medications for diabetes did not change these results. Taken together, this suggests that practitioners should not wait until they diagnose an older patient with diabetes to discuss information and concepts to promote good health outcomes, rather they should intervene to increase literacy at all levels of glycemic control. This is particularly important given that a recent meta-analysis found even slight increases in diabetes indicators increases the risk for cardiovascular disease, coronary heart disease and/or stroke in individuals with prediabetes (37).
Third, this study extends previous work (4, 13) demonstrating the importance of adequate levels of financial literacy for preventing cost-related nonadherence in individuals with diabetes. More specifically, our results revealed that lower levels of financial literacy were associated with higher levels of hemoglobin A1c, suggestive of longer-term glycemic instability, in individuals with and without diabetes. Thus, the association of literacy with diabetes indicators does not appear to be confined to total and health literacy but may extend to include financial literacy. Sensitivity analyses revealed a similar association between financial literacy and hemoglobin A1c independent of diabetes status; however, this association did not reach the statistical significance likely due to the reduced sample size. Whether these associations reflect cost-related nonadherence to a healthy lifestyle or portend development of incident diabetes in individuals at preclinical levels of risk is the focus of ongoing work in our group.
While the basis of the association between literacy and diabetes indicators in older adults remains unclear, literacy promotes engagement in positive health behaviors across the lifespan which may lead to better health status in older age. For example, literacy has been associated with physical and cognitive activity (1), smoking cessation (38), increased physical functioning, and slower declines in physical functioning over time (39). Although we did not assess specific health promoting behaviors associated with diabetes and/or blood sugar management, our reported relationship between literacy and diabetes indicators remained significant after controlling for factors associated with physical and mental health status including hypertension, global cognitive functioning, and depression. Additionally, these relationships were independent of diabetes status. There is also evidence that literacy is associated with increases in disease-specific knowledge (35, 36, 40), particularly when older adults are diagnosed with a disease and exposed to the health care system. Our data would suggest, however, that literacy is involved with health indicators even before a medical condition explicitly manifests or is diagnosed. Thus, our findings suggest that higher literacy levels may provide health benefits even for older adults without overt disease. Future studies are needed to address this; however, we suspect that the benefits of increasing literacy may extend to a host of chronic diseases among older adults.
This study has a number of strengths including a detailed assessment of literacy, with a focus on domain-specific aspects that are important to successful aging regardless of diabetes status. We were able to use data from a fairly large cohort of community dwelling individuals free of dementia and conduct a series of sensitivity analyses considering the role of diabetes status. Furthermore, by adjusting for key characteristics known to impact literacy including global cognitive functioning, we were able to determine the independent relationship that literacy had to diabetes indicators. This study, however, is cross-sectional and does not address causality. Additionally, sensitivity analyses did not reveal associations between literacy and diabetes. While this is not uncommon in the literature (32–34), it may be due, in part, to an insufficient sample size of individuals meeting diabetes status criteria. Furthermore, meeting our study criteria for diabetes is not the same as meeting clinical criteria for diabetes. Our participants were primarily non-Latino White and highly educated, thus, our results may lack generalizability; more work is needed in racially and ethnically diverse populations. Even with these limitations, our findings associating literacy with diabetes indicators independent of diabetes status provide support for promoting literacy in older adults across the spectrum of health and disease.
What is already known on this subject?
Lower levels of health and financial literacy are associated with less frequent participation in health promoting behaviors and poorer decision making. Despite the fact that lower health literacy, and to a lesser extent financial literacy, have been associated with poorer self-management of diabetes and nonadherence to glucose-lowering agents, no study, to our knowledge, has examined the association of literacy with diabetes indicators (i.e., hemoglobin A1c and/or glucose levels) in older adults without diabetes. This is particularly important given that older adults without diabetes but with elevated levels of diabetes indicators may benefit from improvements in literacy and subsequently health promoting behaviors to reduce diabetes risk.
What this study adds?
In a community-based sample of more than 900 non-demented older adults, lower levels of literacy, particularly health literacy, were associated with higher levels of hemoglobin A1c and blood glucose. Lower levels of financial literacy were associated with higher levels of hemoglobin A1c. These findings were independent of age, sex, education, other cardiovascular risk factors and global cognitive functioning; furthermore, they were not driven by persons with self-reported diabetes and/or medications for diabetes. Results suggests that practitioners should not wait until they diagnose an older patient with diabetes to discuss information and concepts to promote good health outcomes, rather they should intervene to increase literacy at all levels of glycemic control.
Acknowledgements
The study was supported by National Institute on Aging (grant number R01AG17917, R01AG34374 and R01AG33678 and K01AG050823). The authors thank the participants in the Rush Memory and Aging Project and the staff of the Rush Alzheimer’s Disease Center. More information regarding obtaining data from the Rush Memory and Aging Project for research use can be found at the RADC Research Resource Sharing Hub (www.radc.rush.edu).
Footnotes
Competing Interest
None declared.
References
- 1.Bennett JS, Boyle PA, James BD, Bennett DA. Correlates of health and financial literacy in older adults without dementia. BMC Geriatr. 2012;12:30. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Boyle PA, Yu L, Wilson RS, Segawa E, Buchman AS, Bennett DA. Cognitive decline impairs financial and health literacy among community-based older persons without dementia. Psychol Aging. 2013;28(3):614–24. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.James BD, Boyle PA, Bennett JS, Bennett DA. The impact of health and financial literacy on decision making in community-based older adults. Gerontology. 2012;58(6):531–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Patel MR, Kruger DJ, Cupal S, Zimmerman MA. Effect of Financial Stress and Positive Financial Behaviors on Cost-Related Nonadherence to Health Regimens Among Adults in a Community-Based Setting. Prev Chronic Dis. 2016;13:E46. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Center for Disease Control and Prevention (CDC). National Diabetes Statistics Report. Atlanta, GA: U.S: Dept of Health and Human Services; 2017. [Google Scholar]
- 6.Lusardi A, Mitchelli O. Financial literacy and retirement preparedness: Evidence and implications for financial education. Business Economics. 2007;42:35–44. [Google Scholar]
- 7.Williams MV, Parker RM, Baker DW, Parikh NS, Pitkin K, Coates WC, et al. Inadequate functional health literacy among patients at two public hospitals. JAMA. 1995;274(21):1677–82. [PubMed] [Google Scholar]
- 8.Morris NS, Maclean CD, Littenberg B. Change in health literacy over 2 years in older adults with diabetes. Diabetes Educ. 2013;39(5):638–46. [DOI] [PubMed] [Google Scholar]
- 9.Wilson RS, Yu L, James BD, Bennett DA, Boyle PA. Association of financial and health literacy with cognitive health in old age. Neuropsychol Dev Cogn B Aging Neuropsychol Cogn. 2017;24(2):186–97. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Yu L, Wilson RS, Han SD, Leurgans S, Bennett DA, Boyle PA. Decline in Literacy and Incident AD Dementia Among Community-Dwelling Older Persons. J Aging Health. 2017:898264317716361. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Bostock S, Steptoe A. Association between low functional health literacy and mortality in older adults: longitudinal cohort study. BMJ. 2012;344:e1602. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Nguyen HT, Kirk JK, Arcury TA, Ip EH, Grzywacz JG, Saldana SJ, et al. Cognitive function is a risk for health literacy in older adults with diabetes. Diabetes Res Clin Pract. 2013;101(2):141–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Rodriguez KM. Intrinsic and extrinsic factors affecting patient engagement in diabetes self-management: perspectives of a certified diabetes educator. Clin Ther. 2013;35(2):170–8. [DOI] [PubMed] [Google Scholar]
- 14.Capoccia K, Odegard PS, Letassy N. Medication Adherence With Diabetes Medication: A Systematic Review of the Literature. Diabetes Educ. 2016;42(1):34–71. [DOI] [PubMed] [Google Scholar]
- 15.Schillinger D, Grumbach K, Piette J, Wang F, Osmond D, Daher C, et al. Association of health literacy with diabetes outcomes. JAMA. 2002;288(4):475–82. [DOI] [PubMed] [Google Scholar]
- 16.Brega AG, Ang A, Vega W, Jiang L, Beals J, Mitchell CM, et al. Mechanisms underlying the relationship between health literacy and glycemic control in American Indians and Alaska Natives. Patient Educ Couns. 2012;88(1):61–8. [DOI] [PubMed] [Google Scholar]
- 17.Sarkar U, Karter AJ, Liu JY, Moffet HH, Adler NE, Schillinger D. Hypoglycemia is more common among type 2 diabetes patients with limited health literacy: the Diabetes Study of Northern California (DISTANCE). J Gen Intern Med. 2010;25(9):962–8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Lamar M, Resnick SM, Zonderman AB. Longitudinal changes in verbal memory in older adults: distinguishing the effects of age from repeat testing. Neurology. 2003;60(1):82–6. [DOI] [PubMed] [Google Scholar]
- 19.Watson NL, Rosano C, Boudreau RM, Simonsick EM, Ferrucci L, Sutton-Tyrrell K, et al. Executive function, memory, and gait speed decline in well-functioning older adults. J Gerontol A Biol Sci Med Sci. 2010;65(10):1093–100. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Pappas C, Andel R, Infurna FJ, Seetharaman S. Glycated haemoglobin (HbA1c), diabetes and trajectories of change in episodic memory performance. J Epidemiol Community Health. 2017;71(2):115–20. [DOI] [PubMed] [Google Scholar]
- 21.Rajan KB, Arvanitakis Z, Lynch EB, McAninch EA, Wilson RS, Weuve J, et al. Cognitive decline following incident and preexisting diabetes mellitus in a population sample. Neurology. 2016;87(16):1681–7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Bennett DA, Launer LJ. Longitudinal epidemiologic clinical-pathologic studies of aging and Alzheimer’s disease. Current Alzheimer research. 2012;9(6):617–20. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Bennett DA, Schneider JA, Buchman AS, Barnes LL, Boyle PA, Wilson RS. Overview and findings from the rush Memory and Aging Project. Current Alzheimer research. 2012;9(6):646–63. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Boyle PA, Yu L, Buchman AS, Bennett DA. Risk Aversion is Associated with Decision Making among Community-Based Older Persons. Front Psychol. 2012;3:205. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.McKhann G, Drachman D, Folstein M, Katzman R, Price D, Stadlan EM. Clinical diagnosis of Alzheimer’s disease: report of the NINCDS-ADRDA Work Group under the auspices of Department of Health and Human Services Task Force on Alzheimer’s Disease. Neurology. 1984;34(7):939–44. [DOI] [PubMed] [Google Scholar]
- 26.Medi-Span. Master Drug Data Base Documentation Manual Indianapolis, IN; 1995. [Google Scholar]
- 27.Colosia AD, Palencia R, Khan S. Prevalence of hypertension and obesity in patients with type 2 diabetes mellitus in observational studies: a systematic literature review. Diabetes Metab Syndr Obes. 2013;6:327–38. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Shah RC, Wilson RS, Bienias JL, Arvanitakis Z, Evans DA, Bennett DA. Relation of blood pressure to risk of incident Alzheimer’s disease and change in global cognitive function in older persons. Neuroepidemiology. 2006;26(1):30–6. [DOI] [PubMed] [Google Scholar]
- 29.Kohout FJ, Berkman LF, Evans DA, Cornoni-Huntley J. Two shorter forms of the CES-D (Center for Epidemiological Studies Depression) depression symptoms index. Journal of aging and health. 1993;5(2):179–93. [DOI] [PubMed] [Google Scholar]
- 30.Wilson RS, Barnes LL, Mendes de Leon CF, Aggarwal NT, Schneider JS, Bach J, et al. Depressive symptoms, cognitive decline, and risk of AD in older persons. Neurology. 2002;59(3):364–70. [DOI] [PubMed] [Google Scholar]
- 31.Radloff LS. The CES-D Scale: a self-report depression scale for research in the general population. Applied Psychological Measurement 1977;1:385–401. [Google Scholar]
- 32.Cavanaugh K, Huizinga MM, Wallston KA, Gebretsadik T, Shintani A, Davis D, et al. Association of numeracy and diabetes control. Ann Intern Med. 2008;148(10):737–46. [DOI] [PubMed] [Google Scholar]
- 33.Morris NS, MacLean CD, Littenberg B. Literacy and health outcomes: a cross-sectional study in 1002 adults with diabetes. BMC Fam Pract. 2006;7:49. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34.Rothman R, Malone R, Bryant B, Horlen C, DeWalt D, Pignone M. The relationship between literacy and glycemic control in a diabetes disease-management program. Diabetes Educ. 2004;30(2):263–73. [DOI] [PubMed] [Google Scholar]
- 35.Bains SS, Egede LE. Associations between health literacy, diabetes knowledge, self-care behaviors, and glycemic control in a low income population with type 2 diabetes. Diabetes Technol Ther. 2011;13(3):335–41. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 36.Gazmararian JA, Williams MV, Peel J, Baker DW. Health literacy and knowledge of chronic disease. Patient Educ Couns. 2003;51(3):267–75. [DOI] [PubMed] [Google Scholar]
- 37.Huang Y, Cai X, Mai W, Li M, Hu Y. Association between prediabetes and risk of cardiovascular disease and all cause mortality: systematic review and meta-analysis. BMJ. 2016;355:i5953. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 38.Stewart DW, Adams CE, Cano MA, Correa-Fernandez V, Li Y, Waters AJ, et al. Associations between health literacy and established predictors of smoking cessation. Am J Public Health. 2013;103(7):e43–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 39.Smith SG, O’Conor R, Curtis LM, Waite K, Deary IJ, Paasche-Orlow M, et al. Low health literacy predicts decline in physical function among older adults: findings from the LitCog cohort study. J Epidemiol Community Health. 2015;69(5):474–80. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 40.Wolf MS, Seligman H, Davis TC, Fleming DA, Curtis LM, Pandit AU, et al. Clinic-based versus outsourced implementation of a diabetes health literacy intervention. J Gen Intern Med. 2014;29(1):59–67. [DOI] [PMC free article] [PubMed] [Google Scholar]