High fasting C-peptide levels and insulin resistance in non-lean & non-obese (BMI >19 to < 25 kg/m2) Asian Indians with type 2 diabetes are independently associated with high intra-abdominal fat and liver span

Abstract

Background and objectives: We aimed to compare C-peptide levels & measures of insulin resistance in non-lean & non-obese Asian Indian patients with type 2 diabetes (T2DM) vs. non-lean, non-diabetic controls and to correlate with anthropometric measures, volumes of abdominal adipose tissue depots, pancreas, & liver span.

Methods: Non-lean, non-obese (BMI >19 and < 25 kg/m²) Asian Indian patients with T2DM, (cases n, 87), diagnosed within one year, on metformin mono therapy, were compared to BMI-matched non-diabetic subjects (controls, n, 37). Measures of glycaemia, insulin and C-peptide levels (fasting and post-prandial), lipid profile, and hepatic transaminases were analysed. Abdominal adipose tissue volumes [subcutaneous & intra-abdominal], pancreatic volume and liver span were assessed using 1.5 Tesla MRI scan.

Results: In cases, the mean values of HbA1c, fasting and post prandial insulin and C-peptide levels, and 3 measures of insulin resistance were significantly higher than controls, but not for HOMA-B. Higher fasting C-peptide levels correlated significantly with HOMA-IR (r = 0.42, p < 0.001), Fasting Insulin Resistance Index (r = 0.42, p < 0.001), Bennett's Index (r = 0.38, p < 0.05), and volumes of SCAT and IAAT only in cases. The independent predictors of higher fasting C-peptide level were IAAT volume (β = 0.057; p = 0.002), liver span (β = 0.057, p = 0.005) and fasting insulin levels (β = 0.35, p = 0.02).

Conclusion: Higher fasting and post-prandial C-peptide levels and surrogate measures of insulin resistance in non-obese Asian Indian patients with T2DM are independently associated with IAAT volume and liver span.

Keywords: C-peptide; Insulin resistance; Non-lean Asian indians; Non-obese; Type 2 diabetes.