Indicators for insulin therapy in late elderly patients with type 2 diabetes mellitus - The relationship between plasma C-peptide on glucagon load test and insulin therapy

Abstract

Aim: Elderly patients with type 2 diabetes (DM2) are increasing in Japan. They have many difficulties related to advanced age, so it is difficult to determine the appropriate therapy, insulin or oral hypoglycemic agents (OHA). The most appropriate indicators for insulin therapy concerning pancreatic β cell function in extremely elderly cases of DM2 were investigated. Methods: The subjects were 43 late elderly patients older than 75 years old with DM2, who were non-obese and without advanced hepatic disease or renal dysfunction. They underwent a 1 mg glucagon load test during hospitalization. After discharge, the therapeutic modality was evaluated. Results: Acceptable control was obtained in 25 cases by OHA (group OHA), 18 cases required treatment with insulin (group I) because they could not achieve acceptable control by only OHA. Fasting CPR and CPR 6 minutes after glucagon loading (CPR6), CPR increment and CPI (fasting CPR/fasting plasma glucose x 100) were significantly lower in group I (p< 0.001). On the receiver operator characteristic curve analysis to discriminate the group I, the areas under the curve of CPI, CPR6, FCPR and CPR increment in group I, were 0.973, 0.964, 0.922 and 0.858 respectively. At 0.9 of CPI, the efficiency ((true positive + true negative)/total) (93.0%) and the sum of the sensitivity (88.9%) and the specificity (96.0%) were highest. Conclusion: It is suggested that CPI less than 0.9, shows a need for insulin therapy in late elderly patients with DM2. This suggests that CPI can be utilized to indicate the need for insulin therapy without performing glucagon load tests.