Insulin secretory capacity in Singapore diabetic subjects

The determination of serum C-peptide has been found to be a sensitive indicator of endogenous insulin secretion, and serves to define diabetic patients who require insulin therapy i.e., insulin-dependent (Type I, IDDM) and those non-insulin dependent (Type II, NIDDM). The aim of our study is to establish the types of diabetes mellitus with C-peptide measurement in a group of diabetic subjects on different modes of therapy. Eighty-eight diabetic patients (60 males, 28 females) were studied. Thirty-four were on insulin (age 40 +/- 2 years; means +/- SEM), 35 on oral agents (54 +/- 1 years), and 19 on diet alone (46 +/- 3 years). Twenty healthy subjects (10 males, 10 females) serve as normal controls (37 +/- 3 years). Blood samples for serum C-peptide and blood glucose estimations were obtained after an overnight fast and one hour after a 75 grams oral glucose load. Fasting C-peptide levels obtained for the various groups were: 0.62 +/- 0.07 (nmol/L, means +/- SEM) (normal), 0.16 +/- 0.02 (insulin), 0.79 +/- 0.06 (oral), 2.15 +/- 0.15 (diet). The C-peptide values after oral glucose were 1.80 +/- 0.20 (normal), 0.23 +/- 0.05 (insulin), 1.72 +/- 0.02 (oral), 2.15 +/- 0.15 (diet). Both the fasting and post-glucose C-peptide concentrations were significantly lower (p less than 0.001) in the insulin group compared to the normals, whereas values for the diet and oral groups were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)