Waist circumference early predictor of diabetes for Black adults
Waist circumference, as well as amounts of visceral fat and liver fat, were better predictors of diabetes development than HbA1c among Black adults with normal glucose levels, according to an analysis of data from the Jackson Heart Study.
“Black American populations are diagnosed with diabetes earlier in life, and earlier age at diabetes onset is associated with greater risk for cardiovascular disease and death,” Joshua J. Joseph, MD, MPH, FAHA, assistant professor of medicine in the division of endocrinology, diabetes and metabolism at The Ohio State University Wexner Medical Center, told Healio.
“Identifying Black Americans at higher risk for diabetes prior to the development of prediabetes will allow for changes to lifestyle behaviors to prevent prediabetes and, ultimately, diabetes, advancing health equity in diabetes. We chose to evaluate adiposity as a marker that is known to be associated with increased risk of diabetes to determine if any of the measures were better or worse at predicting risk of diabetes among individuals with normal fasting glucose and HbA1c vs. individuals with prediabetes.”
Joseph and colleagues analyzed data from two samples of Black adults without diabetes participating in the Jackson Heart Study, a prospective cohort study of CVD among Black adults from the tri-county area of metropolitan Jackson, Mississippi. Enrollment and baseline examinations were performed from 2000 to 2004, with two subsequent in-person follow-up examinations from 2005-2008 and 2009-2013.
The first sample consisted of participants without diabetes with data on anthropometric and biomarker measures (adiponectin, leptin and ratio of leptin to adiponectin) at first exam with follow-up at second exam (n = 2,422). The second sample consisted of participants without diabetes with data on anthropometric and body composition (visceral adipose tissue, subcutaneous adipose tissue and liver attenuation) at second exam with follow-up at third exam (n = 1,537). Researchers estimated HRs for diabetes using interval-censored Cox modeling, adjusting for traditional risk factors.
The study was published in the Journal of the American Heart Association.
Between first and second exams (median follow-up, 5 years), 300 participants from the first sample developed diabetes, for an incidence rate of 24.6 per 1,000 person-years. After adjustment for age, sex, education, occupation, smoking status and alcohol intake, physical activity, diet, systolic blood pressure and BMI, each 1 U standard deviation (SD) increase in waist circumference, log-leptin and log-leptin to adiponectin ratio was associated with a 56%, 76% and 95% higher risk for of diabetes, respectively (P < .0001 for all). Glycemic status modified the association between waist circumference and risk for incident diabetes, with the effect size greater among participants with normoglycemia. After simultaneous adjustment for other measures of adiposity, a 1 SD increase in waist circumference (HR = 2.41; 95% CI, 1.32-4.37) and log adiponectin (HR = 0.66; 95% CI, 0.47-0.93) remained significant among participants with normoglycemia.
In the second sample, researchers found a 1 SD increase in BMI (HR = 15; 95% CI, 2.37-94.4) and liver attenuation (HR = 0.41; 95% CI, 0.2-0.81) remained significant as predictors of diabetes among participants with normoglycemia. Among participants with prediabetes, a 1 SD increase in liver attenuation (HR = 0.74; 95% CI, 0.64-0.86) and visceral adipose tissue (HR = 1.31; 95% CI, 1.04-1.64) were predictors of incident diabetes.
“Based on our previous work, we felt that adiposity may be a better predictor than HbA1c among those with an HbA1c of less than 5.7% and normal fasting glucose less than 100 mg/dL, but it was still surprising to see that waist circumference, visceral fat and liver fat were better than HbA1c at predicting diabetes,” Joseph told Healio. “The take-home message for clinicians is to consider adding waist circumference to the vitals that are taken during office visits. For individuals with higher waist circumference but normal blood glucose and HbA1c, it is important to reinforce the importance of healthy lifestyle behaviors, such as the American Heart Association Life’s Simple 7.”
Joseph said understanding which people are at higher risk for diabetes prior to developing prediabetes, combined with programming to increase modifiable lifestyle behaviors, may be a “key pillar” in advancing health equity in diabetes.
Wang MC, et al. JAMA Intern Med. 2021;doi:10.1001/jamainternmed.2021.4945.