Abstract
This cross-sectional study uses data from the National Health and Nutrition Examination Survey to assess age at diagnosis of diabetes by race/ethnicity in the US from 2011 to 2018.
The prevalence of diabetes in the US has increased substantially over the past 2 decades and is higher among non-Hispanic Black and Hispanic adults than non-Hispanic White adults.1 Earlier age at diabetes onset is associated with greater risk of cardiovascular disease and death2 and may contribute to observed racial/ethnic disparities in diabetes complications. Therefore, we compared the self-reported age at diabetes diagnosis by race/ethnicity in the US.
Methods
We performed a cross-sectional study pooling data from four 2-year cycles of the National Health and Nutrition Examination Survey, from January 1, 2011, to December 31, 2018. The Northwestern University institutional review board determined this study to be exempt from review and informed consent due to the use of deidentified data. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.
Data were combined starting with the 2011-2012 survey because that was the first cycle to include self-identified Asian respondents. We included all adults (aged ≥20 years) who self-reported a history of diabetes and age at diagnosis. Self-reported race/ethnicity was assessed as a social construct to investigate health disparities. We computed the mean and median age at diagnosis of diabetes overall and by race/ethnicity, examining group differences using t tests and quantile regression, respectively. We additionally determined the proportion of adults in each racial/ethnic group with age at diagnosis of diabetes before age 40, 35, and 30 years. In the primary analysis, we excluded adults with a likely diagnosis of type 1 diabetes, defined by self-report of diagnosis before age 30 years and on insulin monotherapy.3 In a sensitivity analysis, we included all adults with self-reported diabetes. All reported statistics are weighted to be representative of the civilian noninstitutionalized US population. All analyses accounted for the complex sampling design of the National Health and Nutrition Examination Survey. Statistical analyses were conducted from February 22 to June 23, 2021, using Stata, version 15.1 (StataCorp LLC). All P values were 2-sided, and P < .05 was considered statistically significant.
Results
The study sample included 3022 participants (1586 men and 1436 women; 946 non-Hispanic White participants; weighted mean [SD] age, 61.1 [0.3] years) who reported diabetes, representing 22 844 326 adults (Table 1). The mean age at diabetes diagnosis overall was 49.9 years (95% CI, 49.2-50.7 years) (Table 2). Relative to non-Hispanic White adults (mean age, 51.8 years; 95% CI, 50.8-52.9 years), Mexican American and non-Hispanic Black adults reported a significantly younger mean age at diagnosis (mean age, 47.2 years; 95% CI, 46.1-48.4 years and 44.9 years; 95% CI, 43.4-46.4 years, respectively; P < .001), but non-Hispanic Asian adults did not (mean age, 50.5 years; 95% CI, 48.4-52.6 years). The weighted proportion of adults with diabetes diagnosed before age 40 years was greater among Mexican American adults (35.0%) and non-Hispanic Black adults (25.1%) compared with non-Hispanic White adults (14.4%) (P ≤ .001). In the sensitivity analysis including all adults with self-reported diabetes, a similar pattern in age at diabetes diagnosis was observed.
Table 1. Demographic Characteristics of Adults With Self-reported Diabetes by Race and Ethnicity in the US, 2011-2018.
| Characteristic | Overall (N = 3022) | Non-Hispanic White (n = 946) | Non-Hispanic Black (n = 805) | Mexican American (n = 508)a | Non-Hispanic Asian (n = 339) |
|---|---|---|---|---|---|
| Weighted, No.b | 22 844 326 | 13 613 262 | 3 295 576 | 2 252 173 | 1 334 882 |
| Age, mean (SD)c | 61.1 (0.3) | 63.1 (0.4) | 59.4 (0.5) | 55.3 (0.9) | 60.4 (1.0) |
| Women, % | 48.3 | 46.3 | 57.2 | 49.5 | 48.2 |
| Men, % | 51.7 | 53.7 | 42.8 | 50.5 | 51.8 |
| Education, % | |||||
| Less than high school | 21.8 | 14.2 | 24.6 | 55.1 | 23.4 |
| High school graduate | 25.5 | 26.9 | 25.8 | 21.5 | 15.8 |
| Any college | 52.7 | 58.9 | 49.6 | 23.3 | 60.8 |
| Hypertension, %d | 70.2 | 71.9 | 77.7 | 57.3 | 56.6 |
| Obesity, %d | 55.8 | 59.5 | 59.9 | 56.1 | 16.5 |
Oversampled relative to other Hispanic populations due to the National Health and Nutrition Examination Survey sampling design.
All statistics are weighted to be representative of the US population.
At time of survey.
Based on self-reported data.
Table 2. Distribution of Age at Diabetes Diagnosis by Race and Ethnicity in the United States, 2011-2018.
| Variable | Overall (N = 3022) | Non-Hispanic White (n = 946) | Non-Hispanic Black (n = 805) | Mexican American (n = 508)a | Non-Hispanic Asian (n = 339) |
|---|---|---|---|---|---|
| Summary measures of age at diabetes diagnosisb | |||||
| Mean (95% CI) | 49.9 (49.2-50.7) | 51.8 (50.8-52.9) | 47.2 (46.1-48.4) | 44.9 (43.4-46.4) | 50.5 (48.4-52.6) |
| P value for differencec | NA | 1 [Reference] | <.001 | <.001 | .25 |
| Median | 50 | 52 | 48 | 45 | 50 |
| P value for differencec,d | NA | 1 [Reference] | <.001 | <.001 | .07 |
| Proportion of adults with diabetes diagnosis at varying agesb | |||||
| Diagnosis at <40 y, % | 19.4 | 14.4 | 25.1 | 35.0 | 19.3 |
| P value for differencec | NA | 1 [Reference] | .001 | <.001 | .10 |
| Diagnosis at <35 y, % | 12.2 | 9.3 | 15.5 | 21.0 | 13.2 |
| P value for differencec | NA | 1 [Reference] | .006 | <.001 | .10 |
| Diagnosis at <30 y, % | 5.9 | 4.4 | 7.3 | 10.1 | 7.4 |
| P value for differencec | NA | 1 [Reference] | .06 | .008 | .14 |
Abbreviation: NA, not applicable.
Oversampled relative to other Hispanic populations owing to the National Health and Nutrition Examination Survey sampling design.
All statistics are weighted to be representative of the US population.
P values were calculated using the group with the oldest mean age at diagnosis as the referent (non-Hispanic White adults).
Based on quantile regression.
Discussion
In this cross-sectional study of a nationally representative sample of US adults from 2011-2018, the mean age at diabetes diagnosis was 4 to 7 years earlier in non-Hispanic Black and Mexican American adults than in non-Hispanic White adults. In addition, more than 25% of non-Hispanic Black and Mexican American adults with diagnosed diabetes reported diagnosis before age 40 years. The lack of observed differences between non-Hispanic White and non-Hispanic Asian adults may mask heterogeneity across different Asian subgroups.4 Additional limitations of this work include reliance on self-reported data, which are subject to recall bias and do not capture undiagnosed diabetes.
Earlier age at diabetes diagnosis among non-Hispanic Black and Mexican American adults is attributable to a combination of clinical, behavioral, and social factors5 and may potentially contribute to observed disparities in diabetes-related microvascular and macrovascular complications and premature mortality. Accordingly, there may be benefit to initiating intensive lifestyle changes starting earlier in adulthood.6 Efforts to prevent and manage diabetes earlier in the life course may help reduce the substantial premature morbidity and mortality associated with diabetes.
References
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