Dual Energy X‐Ray Absorptiometry Reveals Differential Glycemic Implications of Adiposity in Underweight, Normal Weight, and Overweight South African Women With Newly‐Diagnosed Diabetes

AIMS: Although diabetes typically arises in middle-aged, overweight/obese individuals, African populations exhibit disproportionately elevated prevalence rates in young adults with underweight or normal weight. However, little is known about the contribution of adiposity to diabetes in this context. We thus sought to characterise the relationships between body composition and A1c in young African women newly-diagnosed with diabetes in the setting of underweight, normal weight and overweight/obesity. METHODS: Baseline assessment for a trial identified 379 women (median age 22.4 years; median A1c 7.0%) with previously undiagnosed diabetes in Soweto, South Africa. Women were stratified into BMI categories of overweight/obese (BMI ≥ 25; n = 192), normal weight (18.5 ≤ BMI < 25; n = 158), and underweight (BMI < 18.5; n = 29), and underwent Dual Energy X-ray Absorptiometry (DEXA) scanning to evaluate total and regional adiposity. RESULTS: All body composition measures progressively increased from underweight to normal weight to overweight/obese (all p < 0.001), whereas A1c did not differ between the groups. Fat mass, gynoid fat, trunk fat, and leg fat were each associated with A1c in underweight diabetes (all r ≥ 0.48, p ≤ 0.01) but not in normal weight or overweight/obese groups. Upon covariate adjustment, fat mass (β = 0.18, p = 0.007), gynoid fat (β = 0.77, p = 0.03), trunk fat (β = 0.46, p = 0.01), and leg fat (β = 0.30, p = 0.01) were each independently associated with A1c in underweight diabetes, with no such associations in normal weight and overweight/obese groups. CONCLUSION: In young South African women with newly-diagnosed diabetes, adiposity relates to A1c only in those who are underweight, but paradoxically not in those with normal weight or overweight/obesity, potentially suggestive of biologic differences from diabetes in other populations.