Body Mass Index, Fasting Plasma Glucose Levels, and C-peptide Levels as Predictors of the Future Insulin Use in Japanese Type 2 Diabetic Patients

Insulin therapy represents the most effective and reliable means of achieving satisfactory glycemic control. However, few studies have evaluated the predictors of future insulin use. The purpose of this study was to investigate the predictors of future insulin use in type 2 diabetic patients. In this study, we conducted a chart review of 158 Japanese type 2 diabetic patients admitted to our hospital for stringent glycemic control. Of the 158 subjects, 92 satisfied the inclusion criteria for this study. We assessed the associations between baseline BMI, fasting plasma glucose levels (FPG) and serum and urinary C-peptide levels (sCPR and uCPR), and insulin usage at 6 months after discharge. We also computed the areas under the curve (AUCs) in receiver operator characteristic (ROC) curves for each predictor to predict the future insulin use. After adjustment for gender, age, and BMI, the multivariable odds ratios (ORs) for future insulin use in the highest tertile as compared with lowest tertile were 0.12 for BMI (95% confidence interval (CI), 0.03-0.52), 17.0 for FPG (95% CI, 3.27-88.7), 0.12 for sCPR (95% CI, 0.02-0.71), and 0.03 for uCPR (95% CI, 0.00-0.24). Prediction analyses showed that the AUCs for BMI, FPG, sCPR, and uCPR were 0.73, 0.76, 0.74, and 0.78, respectively, which suggests that the predictive abilities of these predictors do not differ substantially. In conclusion, this study suggests that BMI, FPG, sCPR, and uCPR are strong predictors of the future insulin use in type 2 diabetic patients.