Aims/Launch Type 2 diabetes is a progressive disease seen as a a yearly drop in insulin secretion; nevertheless no definitive proof exists showing the partnership between reduced insulin secretion and the necessity for insulin treatment. Glucagon‐launching CPR increment (ΔCPR) fasting CPR (FCPR) CPR 2?h after breakfast time (CPR2h) the proportion of FCPR to FPG (CPI) CPI 2?h after breakfast time (CPI2h) and secretory device of islets in transplantation (Fit) were submitted for the analyses. Recipient operating quality (ROC) and multiple logistic analyses for these CPR indices had been carried out. Outcomes Many CPR beliefs were significantly low in the MDI group weighed against the OHA by itself or BOT groupings. ROC and multiple logistic analyses disclosed that post‐prandial CPR indices (CPR2h and CPI2h) had been the most dependable CPR markers to recognize patients requiring MDI. Conclusions Postprandial CPR level after breakfast is the most useful index for identifying patients with non‐obese type 2 diabetes who require MDI therapy. Keywords: C‐peptide Meal weight Multiple daily insulin injection Introduction Type 2 diabetes mellitus is usually a progressive disease characterized by a yearly decline in insulin secretion1. Parients with type 2 diabetes will eventually require insulin therapy. This insulin therapy can involve numerous regimens including basal insulin‐supported oral therapy (BOT) or multiple daily insulin injection (MDI). The American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) have published a consensus statement4 regarding the management of hyperglycemia in type 2 diabetes. This includes a practical algorithm of the therapy based on blood glucose and glycated hemoglobin (HbA1c) which progresses from oral hypoglycemic agent (OHA) to basal insulin therapy and then to MDI. The progression from OHA to MDI in type 2 diabetes is usually assumed to be closely related to the decrease in insulin secretory capacity. In clinical practice whether or not insulin therapy is required for glycemic control is usually a significant issue for patients and physicians yet no useful insulin secretory index for identifying when insulin therapy should be started exists. Recently regarding serum C‐peptide immunoreactivity (CPR) as a marker for predicting insulin requirement in type 2 diabetes several reports have been published5 where useful CPR indices were advocated. In the present study to determine the optimal CPR index for identifying MDI‐requiring BMN673 patients with non‐obese type 2 diabetes we retrospectively analyzed numerous serum CPR values by comparing the values among different diabetes therapy groups which were decided according to our treatment protocol. The protocol consists of rigorous insulin therapy (IIT) and challenge of OHA mainly BMN673 including insulin secretagogues after IIT. Material and Methods Patients Using our department diabetes database we initially selected 1 39 patients with type 2 diabetes who had been hospitalized and treated with insulin for poor glycemic control over a 36‐month period between October 2007 and September 2010. Among this group those with incomplete plasma glucose (PG) values (163 patients) or CPR (89 patients) or those in a preoperative state (109 patients) were excluded leaving 678 patients. Then another 109 patients with conditions influencing CPR assessment or selection of insulin therapy including those with chronic liver disease (37) malignancies (32) dementia (13) acute infections (11) diabetic foot (8) or BMN673 who deviated from the treatment protocol (8) were also excluded from the study leaving 569 patients. Of these 291 non‐obese (body mass index [BMI] of <25) patients with type 2 diabetes were enrolled in the BMN673 study. The mode of treatment at baseline in these cases was OHA alone in 160 patients (a sulfonylurea in 115) insulin in 62 patients Jun (combined with OHA in 21) and no treatment in 69 sufferers. Table?1 displays the baseline clinical type and features of treatment in enrolment in these sufferers. Desk 1 Baseline scientific characteristics of sufferers enrolled in the analysis (n?=291) Treatment Process Treatment proceeded predicated on a 2‐week treatment process. On time?1 a typical diabetes meal 30 of standard bodyweight: 22?×?body elevation (m)2 comprising 62% carbohydrate 16 proteins and 22% body fat (when taking 1600 kcal diet plan each day) was.