Postprandial serum C-peptide value is the optimal index to identify patients with non-obese type 2 diabetes who require multiple daily insulin injection: Analysis of C-peptide values before and after short-term intensive insulin therapy.

Aims/IntroductionType 2 diabetes is a progressive disease characterized by a yearly decline in insulin secretion; however, no definitive evidence exists showing the relationship between decreased insulin secretion and the need for insulin treatment. To determine the optimal insulin secretory index for identifying patients with non-obese type 2 diabetes who require multiple daily insulin injection (MDI), we evaluated various serum C-peptide immunoreactivity (CPR) values. Materials and MethodsWe near-normalized blood glucose with intensive insulin therapy (IIT) over a 2-week period in 291 patients with non-obese type 2 diabetes, based on our treatment protocol. After improving hyperglycemia, we challenged with oral hypoglycemic agent (OHA), and according to the responsiveness to OHA, patients were classified into three therapy groups: OHA alone (n=103), basal insulin plus OHA (basal insulin-supported oral therapy [BOT]; n=56) and MDI (n=132). Glucagon-loading CPR increment (CPR), fasting CPR (FCPR), CPR 2h after breakfast (CPR2h), the ratio of FCPR to FPG (CPI), CPI 2h after breakfast (CPI2h) and secretory unit of islets in transplantation (SUIT) were submitted for the analyses. Receiver operating characteristic (ROC) and multiple logistic analyses for these CPR indices were carried out. ResultsMany CPR values were significantly lower in the MDI group compared with the OHA alone or BOT groups. ROC and multiple logistic analyses disclosed that post-prandial CPR indices (CPR2h and CPI2h) were the most reliable CPR markers to identify patients requiring MDI. ConclusionsPostprandial CPR level after breakfast is the most useful index for identifying patients with non-obese type 2 diabetes who require MDI therapy.