1558-P: Postprandial CPR Index Is Valuable in Assessing Beta-Cell Function in Japanese Patients with Type 2 Diabetes

Residual β-cell function is a key factor in achieving optimal glycemic control in patients with diabetes, Glucagon stimulation test (GST) is secure and reliable to evaluate β-cell function, but is difficult to be examined in usual clinical settings. While F-CPR-index (Fasting C-peptide (CPR) [ng/ml] / glucose[mg/dl] x100) is widely used as a surrogate marker of insulin secretion. We hypothesized postprandial CPR to glucose ratio (P-CPR-index) can be another efficient marker for evaluating β-cell function in patients with type 2 diabetes (T2DM).Five hundred of Japanese T2DM patients with inadequate glycemic control (HbA1c>7.0) were eligible in this study. HbA1c, fasting CPR and glucose, postprandial (120 min after breakfast) CPR and glucose were measured, and then F-CPR-index and P-CPR-index were calculated. GST was performed as follows: 1mg of glucagon was injected intravenously, CPR was determined before and 6 min after injection, GSTΔCPR (CPR [6 min] - CPR [0 min]) was calculated. Factors correlated with GSTΔCPR were analyzed using simple and multiple stepwise regression analysis. P value<0.05 was defined as statistical difference.Average F-CPR-index, P-CPR-index and GSTΔCPR were 1.60<u>+</u>0.95, 2.67<u>+</u>1.92 and 1.93<u>+</u>1.21, respectively. Simple regression analysis showed that GSTΔCPR was significantly correlated with urinary CPR, F-CPR-index and P-CPR-index as well as age, height, body weight (BW), BMI, waist circumference, duration of diabetes, retinopathy, insulin therapy. Multiple stepwise regression analysis revealed that independent factors contributing to GSTΔCPR were P-CPR-index (β= 0.432), BW (β= 0.336), duration of diabetes (β= -0.107), presence of retinopathy (β= -0.121), use of DPP-4i (β= -0.099), metformin (β= -0.109), SGLT2i (β= -0.108, p= 0.002) but not F-CPR-index.Our date suggested that P-CPR-index was valuable and simple method in assessing residual beta-cell function in daily clinical practice.