Diabetes and Insulin Resistance Show Association With Femoral Instead of Abdominal Adipocyte Size in Asian Indians

Abstract

Objectives: Energy intake exceeding expenditure results in adipogenesis, which consists of adipocyte hyperplasia and hypertrophy. Adipocyte hypertrophy is the pathological hallmark of ‘sick fat’ responsible for the development of insulin resistance and diabetes mellitus. In Asian Indians, who show a thin, fat phenotype, the association of adipocyte hypertrophy in various fat depots with insulin resistance and diabetes is not precisely known. The objective of this study is to find an association between adipocyte size of abdominal and thigh fat depot and certain parameters of diabetes mellitus. Material & Methods: In this cross-sectional analytical study, 172 patients were recruited. Abdominal subcutaneous and visceral fat samples were available of 100 patients (Non-diabetics: 56; Diabetics: 44), whereas thigh fat was analyzed in 72 patients (Non-diabetics: 40; Diabetics: 32). All participants had a BMI of less than 30 kg/m² to negate the effect of obesity on adipocyte size. Fasting glucose, insulin, HbA1c, lipid profile including triglycerides, and total cholesterol were measured in all participants, and HOMA-IR was calculated. Adipocyte size in biopsied tissue after fixation was measured with the help of Motic Panthera Moticam 5 trinocular microscope (BA210LED) and Adobe Photoshop CC image analysis tool. Results: Mean adipocyte size in abdominal visceral compartment in diabetics and non-diabetics were 16610.3 ± 889.5 um² and 16129.8 ± 878.5 um² respectively. Whereas, mean adipocyte size in abdominal subcutaneous fat in diabetics and non-diabetics were 15071.0 ± 1261.1 um² and 14356.8 ± 1004.7 um² respectively. Adipocyte size difference of both the abdominal compartments between diabetic and non-diabetic group was statistically non-significant (p= 0.70 & 0.65 in omental and abdominal subcutaneous compartments respectively). Mean adipocyte size of thigh in diabetics and non-diabetics were 13070.2 ± 1416.2 um² and 9020.1 ± 811.1 um² respectively and difference between adipocyte size between both groups was statistically significant (p = 0.01). Thigh Adipocyte size in diabetic subgroup was positively correlated with HOMA -IR (r = 0.4, p = 0.02), triglycerides (r= 0.4, p = 0.03), waist circumference (r = 0.32, p = 0.03). On multivariate linear regression analysis HOMA-IR (β= 0.45, p=0.00), triglycerides (β=0.38, p=0.01) and waist circumference (β=0.35, p=0.02) are predictor of increased adipocyte size. Conclusion: We found that thigh adipocyte size was significantly larger in diabetics in comparison to non-diabetics, whereas no such difference was found in the abdominal fat compartment. In diabetic patients’ thigh, adipocyte size was positively correlated with HOMA-IR, waist circumference, and triglyceride levels, underlining the role of peripheral fat depots in the pathogenesis of diabetes type 2.