Utility of indices using C-peptide levels for indication of insulin therapy to achieve good glycemic control in Japanese patients with type 2 diabetes

Abstract

Aims/Introduction: Type 2 diabetes is progressive in that therapy must be altered over time, which is partly as a result of the progressive loss of pancreatic β‐cell function. To elucidate the relationship between residual endogenous insulin secretion and the necessity of insulin therapy to achieve good glycemic control, indices using serum C‐peptide immunoreactivity (CPR) were analyzed in patients with type 2 diabetes.Materials and Methods: The data of 201 Japanese patients with type 2 diabetes who achieved the target of glycemic control during admission were analyzed retrospectively. Indices using CPR including fasting CPR (FCPR), CPR 6 min after intravenous injection of glucagon (CPR‐6 min), increment of CPR (ΔCPR), secretory unit of islet in transplantation index (SUIT) and C‐peptide index (CPI) were compared between the group requiring insulin (insulin group) and the group not requiring insulin (non‐insulin group). A receiver–operator characteristic (ROC) curve was made, and optimal cut‐off point and likelihood ratio were determined for each index.Results: All indices of CPR were lower in the insulin group compared with those in the non‐insulin group. Likelihood ratios at the optimal point of FCPR, CPR‐6 min, ΔCPR, SUIT, and CPI were 2.0, 2.1, 1.6, 2.3 and 2.8, respectively. Optimal cut‐off point of CPI was 1.1 ng/mg. Sensitivity and specificity at optimal point of CPI were 61 and 78%, respectively.Conclusions: The advantage of CPI of the indices of CPR to select insulin therapy to achieve good glycemic control was shown, but limitations of the predictive abilities of the indices using CPR should be taken into account. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00096.x, 2011)

Retrospective analysis of liraglutide and basal insulin combination therapy in Japanese type 2 diabetes patients: The association between remaining β‐cell function and the achievement of the glycated hemoglobin target 1 year after initiation

“…Fourth, linear associations of CPI with β‐cell function at higher fasting glucose ranges were not investigated. However, fasting glucose levels in the current study participants were similar to or lower than those described in previous studies evaluating remaining β‐cell function to avoid insulin injections and those investigating associations of CPI with other indices of β‐cell function. Despite these limitations, the current findings strongly suggest that liraglutide requires some remaining β‐cell function to exert glucose‐lowering effects, even when used with basal insulin, and suggest that liraglutide and basal insulin therapy requires additional OAD or bolus insulin to achieve ideal HbA1c target.…”

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

“…Funakoshi et al 6 carried out ROC analysis of CPR values as indices indicative of insulin therapy in type 2 diabetes, and found CPI to be superior among several CPR markers. They noted that because CPI could be calculated solely from a 1-point blood sample, it was convenient and less burdensome.…”

“…In clinical practice, whether or not insulin therapy is required for glycemic control is 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 published [5][6][7] , where useful CPR indices were advocated. In the present study, to determine the optimal CPR index for identifying MDI-requiring patients with non-obese type 2 diabetes, we retrospectively analyzed various serum CPR values by comparing the values among different diabetes therapy groups, which were determined according to our treatment protocol.…”

Cross-sectional and Longitudinal Analyses of Factors Contributing to the Progressive Loss of the β-cell Function in Type 2 Diabetes

“…We used 6-min post-glucagon increments in CPR (ΔCPR) as an estimate of β-cell function. In addition, the CPR index (CPI) was calculated by the formula 100×fasting CPR (ng/mL)/fasting plasma glucose (mg/dL) (18)(19)(20). Screening for diabetic retinopathy was performed by ophthalmologists using mydriatic retinal cameras.…”