The Postprandial-to-Fasting Serum C-Peptide Ratio is a Predictor of Response to Basal Insulin-Supported Oral Antidiabetic Drug(s) Therapy: A Retrospective Analysis

INTRODUCTION: Basal insulin is widely recommended for the treatment of type 2 diabetes mellitus (T2DM) patients who are unable to achieve glycemic control with oral antidiabetic drug(s) (OADs). However, some patients are still unable to control their blood glucose levels even when on basal insulin-supported OAD(s) therapy (BOT). The aim of this study was to investigate the factor(s) predicting patient response to BOT. METHODS: A total of 212 patients with T2DM, ranging in age from 18 to 65 years, admitted to the university hospital of Sun Yat-sen University, Guangzhou, China, were enrolled in the study between January 2013 and July 2016. All patients had fasting blood glucose levels of ≥ 10.0 mmol/L despite receiving OAD(s) treatment. According to study design, these patients first received intensive insulin therapy for 2 weeks to attain and maintain their glycemic goals and then were switched to BOT. Responders were defined as subjects who maintained their glycemic targets with BOT for at least 3 months; all others were considered to be non-responders. The characteristics between responders and non-responders were compared. RESULTS: Compared with non-responders, responders had a shorter duration of diabetes (5.1 ± 5.0 vs. and 10.1 ± 3.2 years; P < 0.001) and a higher 2-h postprandial C-peptide-to-fasting C-peptide ratio (2 h-PCP/FCP: 1.95 ± 0.51 vs. 1.67 ± 0.32; P < 0.01). Responders showed a lower proportion of previous treatment with insulin (69/100 vs 40/3; P < 0.001) and sulfonlureas or glinides (116/50 vs 40/0; P <0.001) than non-responders. Multivariate logistic regression analysis showed that previous insulin treatment (odds ratio [OR] 17.677, 95% confidence interval [CI] 5.205–60.027; P < 0.001) and the 2 h-PCP/FCP ratio (OR 0.241, 95% CI 0.058–0.679; P = 0.007) had predictive value. CONCLUSIONS: A higher 2 h-PCP/FCP ratio and a lack of previous insulin treatment increase the likelihood of BOT success.