Abstract
C-peptide is produced in equimolar amounts to insulin and is the best measure of endogenous insulin secretion. This cross-sectional study was conducted in a tertiary hospital of Bangladesh from January 2016 to December 2017 to assess fasting serum c-peptide as a marker of the endogenous insulin secretory capacity in newly diagnosed subjects with type 2 diabetes mellitus (T2DM). 60 newly diagnosed T2DM subjects were investigated along with 30 age-sex matched healthy controls. Fasting c-peptide was significantly higher in T2DM subjects than controls (8.97±5.96 vs. 1.69±0.66 ng/ml). None of the T2DM subjects had subnormal c-peptide, 19 (32%) had normal c-peptide, and 41 (68%) of them had elevated c-peptide levels. Higher fasting plasma glucose (FPG), plasma glucose 2-hours after 75gm oral glucose tolerance test (PG 2H-OGTT) and HbA1c levels were observed in T2DM subjects with elevated c-peptide in comparison to T2DM subjects having normal c-peptide. In T2DM subjects, c-peptide showed significant positive correlations with body mass index (BMI), FPG, PG 2H-OGTT, and HbA1c. This study found higher levels of fasting c-peptide in newly diagnosed T2DM in comparison to nondiabetic controls. None of the T2DM subjects had a subnormal c-peptide level.