Predictive value of postprandial C-peptide for utilizing multiple daily injection therapy in type 2 diabetes

Multiple daily injection (MDI) insulin therapy is an effective method of glycemic control and appropriate assignment to MDI therapy could minimize the risks of hypoglycemia and weight gain. The aim of the present study was to identify factors associated with indication for MDI therapy in type 2 diabetes (T2DM).

We recruited 360 participants with T2DM that were admitted to the Endocrinology Department of Peking University People's Hospital between August 2017 and July 2018. They first underwent intensive insulin therapy, then were switched to an optimized, simpler insulin treatment that aimed to maintain fasting blood glucose between 4.4 and 7.2 mmol/L, without episodes of hypoglycemia. The baseline characteristics of groups administering either MDI or basal/premix insulin were compared and multivariable logistic regression analysis was used to determine the odds ratios (ORs) for factors associated with MDI therapy. Receiver operating characteristic (ROC) curves were then used to identify independent predictors of MDI insulin regimen efficacy.

The mean age of the participants was 57.6 ± 12.9 years, and diabetes duration was 14.2 ± 8.2 years. Two hundred and sixty-seven participants administered basal/premix insulin and 93 underwent MDI therapy, of whom 61.8% and 46.2% were male, respectively (p = 0.01). The duration of diabetes was significantly longer in the MDI group (13.1 ± 7.7 years vs. 17.3 ± 8.7 years; p < 0.01). Fasting plasma glucose (FPG) was higher in the MDI group than in the basal/premix group (8.3 [6.7, 11.3] mmol/L vs. 7.2 [5.7, 9.3] mmol/L; p < 0.01), while the postprandial C-peptide concentration (PCP) was significantly lower in the MDI group (2.6 [1.8, 3.5] ng/mL) compared to the basal/premix group (3.6 [2.5, 6.2] ng/mL, p < 0.01. Multivariable logistic regression analysis suggested that diabetes duration and FPG were positively associated with MDI therapy: OR (95% confidence interval [CI]) 1.06 (1.02, 1.10) and 1.12 (1.02, 1.24), respectively. In addition, PCP was negatively associated with MDI therapy (0.72 [0.60, 0.86]). ROC analysis suggested that a PCP of < 3.1 ng/mL predicted MDI therapy with 59.6% sensitivity and 72.1% specificity.

The results of our study suggest that longer diabetes duration, higher FPG, and lower PCP were associated with necessity for MDI insulin regimen. These findings should assist with the personalization of insulin treatment.