C-peptide response to glucagon in patients with non-insulin-dependent diabetes mellitus

To understand pancreatic beta cell function in patients with non-insulin-dependent diabetes, we analyzed C-peptide response to glucagon in 101 nonketotic patients with onset of diabetes at over 25 years of age and duration of diabetes of more than one year. The fasting serum C-peptide values (FCP), maximal incremental (delta CP) and 6-minute (6'CP) serum C-peptide values after 1 mg of intravenous glucagon administration were not related to age at diagnosis (r = 0.12, 0.06 and 0.10, respectively), duration of diabetes (r = 0.15, 0.05 and 0.10, respectively), fasting plasma glucose concentrations (r = 0.01, 0.18 and 0.12, respectively) or glycohemoglobin (HbA1c, r = 0.13, 0.22 and 0.16, respectively). In contrast, they showed a clear positive correlation with body mass index (BMI, r = 0.36, 0.52 and 0.41, p < 0.001). In order to evaluate the beta cell function in patients with different responses to treatment modalities, a subgroup of 45 patients was divided into three groups: diet successes (DS, n = 14), oral hypoglycemic agent (OHA) successes (OS, n = 19) and OHA failure (OF, n = 12). Among the three groups, patients in the OF group had the longest duration of diabetes (9.4 +/- 1.9 years) and the lowest BMI (19.3 +/- 1.0 kg/m2). Serum C-peptide responses to glucagon were different in the three study groups. Patients in the DS group had the highest response and patients in the OF group had the lowest response. However, the differences in mean FCP, delta CP and 6'CP among the three groups were not statistically significant, and there was a wide overlap of individual C-peptide values.(ABSTRACT TRUNCATED AT 250 WORDS)