Table 2.

Associations Among Literacy and Diabetes Outcomes^a

Study	Sample	Health literacy assessment used	Outcomes reported
Cavanaugh et al.11	398 adult patients with type 1 or type 2 diabetes	REALM; WRAT3; DNT	Lower DNT scores were associated with older age, nonwhite race, fewer years of education, lower reported income, lower literacy and general numeracy skills, and higher HbA1c.
DeWalt et al.12	268 patients with diabetes	REALM	Patients with low literacy had less desire to participate in medical decision making (p < .001) and less diabetes-related knowledge (p < .001). Literacy was not associated with trust, self-efficacy, or diabetes outcomes.
Gazmararian et al.13	653 new Medicare enrollees aged 65 years or older who had at least one chronic disease (115 asthma, 266 diabetes, 166 chronic heart failure, 214 hypertension)	S-TOFHLA	Patients with inadequate health literacy knew significantly less about their disease than those with adequate health literacy. Health literacy was independently related to disease knowledge.
Gazmararian et al.14	1549 patients newly enrolled in Medicare identified as having coronary heart disease, hypertension, diabetes, or hyperlipidemia	S-TOFHLA	Health literacy was related to medication refill adherence (p < .05). Patients with inadequate health literacy skills had increased odds of low refill adherence compared with those with adequate literacy skills (OR = 1.37; 95% CI: 1.08 to 1.74).
Morris et al.15	1002 English-speaking adults with diabetes	S-TOFHLA	Health literacy was not significantly associated with HbA1c (p = .88), systolic blood pressure (p = .39), diastolic blood pressure (p = .59), low density lipoprotein (p = .77), or selfreported diabetes complications.
Powell et al.16	68 patients with type 2 diabetes	REALM	Health literacy was significantly associated with the diabetes knowledge test score (p = .004) and HbA1c (p = .02). Health literacy was not significantly associated with DHBM (p = .29).
Ross et al.17	78 children and adolescents with type 1 diabetes and their mothers	NART; WRAT3; RSPM	The HbA1c of the children correlated with their age (p =.02), social class (p = .03), and NART score of their mother (p = .01). The child's WRAT3 and RSPM did not correlate with HbA1c.
Sarkar et al.18	408 ethnically diverse patients with diabetes	S-TOFHLA	Associations between self-efficacy and self-management were consistent across health literacy and race/ethnicity levels. For each 10% increase in self-efficacy score, patients were more likely to report optimal diet (p < .01), exercise (p < .01), self-monitoring of blood glucose (p < .01), and foot care (p < .01), but not medication adherence (p = .40).
Sarkar et al.19	796 low-income English- and Spanish-speaking patients with diabetes	Self-reported health literacy. Interviewers asked participants how often they have problems learning about their medical condition because of difficulty understanding written information.	Patients with limited self-reported health literacy were more likely to be interested in telephone support (instead of group visits or internet support) than those not reporting literacy deficits.
Schillinger et al.20	408 English- and Spanishspeaking patients who were older than 30 years and had type 2 diabetes	S-TOFHLA in English or Spanish	Patients with inadequate health literacy were less likely to achieve tight glycemic control (p = .05) and were more likely to have poor glycemic control (p = .02) and to report retinopathy (p = .01).
Schillinger et al.21	408 English- and Spanishspeaking patients with diabetes	S-TOFHLA	Patients with inadequate health literacy were more likely to report worse communication in general clarity (p < .01), explanation of condition (p = .03), and explanation of processes of care (p = .03).
Schillinger et al.22	395 low-income patients with diabetes	S-TOFHLA	Health literacy mediated the relationship between education and HbA1c (p < .01)
Sudore et al.23	2512 black and white community-dwelling older people who did not have functional difficulties or dementia	REALM	Limited health literacy was associated with being male, being black, low income, low education, diabetes, depressive symptoms, and fair/poor self-rated health (p < .02). Older people with a sixth-grade reading level or lower were twice as likely to have indicators of poor healthcare access (OR = 1.96; 95% CI: 1.34 to 2.88).
Tang et al.24	149 Chinese patients with type 2 diabetes	Chinese version of the S-TOFHLA	Health literacy was negatively correlated to HbA1c (p < .001)
Williams et al.25	402 patients with hypertension and 114 patients with diabetes	TOFHLA	Knowledge scores for patients with diabetes with inadequate, marginal, or adequate literacy were 5.8 ± 2.1, 6.8 ± 1.9, and 8.1 ± 1.6 (p < .001), and 94% of patients with adequate functional health literacy knew the symptoms of hypoglycemia compared with 50% of those with inadequate health literacy.

^aCI, confidence interval; OR, odds ratio.