Heterogeneity of type 2 diabetes in rural India

The prevalence of diabetes continues to rise in India. The increase in diabetes, which has been previously concentrated in urban areas, is now also occurring in rural India, even though the rural population is predominantly non-obese/lean, undernourished, and physically active. Type 2 diabetes and its pathophysiology (hyperinsulinemia and insulin resistance) among the obese, overnourished, and physically inactive urban populations are very well characterized. However, there is a paucity of such characterization among those non-obese/lean and undernourished. We attempted to characterize type 2 diabetes in the rural Konkan region of India using BMI, body composition, and glycemic parameters.

This cross-sectional study was conducted among 508 subjects with type 2 diabetes who visited the rural tertiary care center. They underwent anthropometry, body composition, and glycemic (i.e., glucose, HbA_1C, and C-peptide) measurements. Various homeostatic model assessment (HOMA) indices for insulin resistance (HOMA-IR), β-cell function (HOMA-β), and insulin sensitivity (HOMA-S) were calculated. The subjects were classified into six groups, with the classification system created by combining BMI with the parameters of central obesity and adiposity for comparisons of the glycemic measurements and the HOMA indices.

The median age, the age at diagnosis, and the duration of type 2 diabetes were 59, 51.5, and 5.2 years, respectively. The BMI distribution showed that 6% were underweight, approximately 46% were normal weight, and 48% were overweight. Central obesity and adiposity were observed in 70% and 56%, respectively. Of those subjects with normal weight, 52% had central obesity, while 29% had excess adipose tissue. The lean group was characterized by a low BMI (mean, 16.7 kg/m²), the absence of central obesity and adiposity, and the lowest C-peptide (median, 463.5 pmol/L) and the lowest insulin resistance. The glycemic characteristics of the overweight, centrally obese, and adipose subjects were similar to those observed in classical type 2 diabetes.

The use of BMI and simple body composition measures led to the identification of a distinct lean phenotype that is characterized by a low BMI, poor insulin secretion, and the absence of central obesity and adiposity. Further research is warranted to understand the pathophysiology and to develop a personalized therapeutic approach for lean subjects with type 2 diabetes. It is time to reconsider the glucocentric, one-size-fits-all approach for type 2 diabetes treatment.