Outcome of Metformin-Facilitated Reinitiation of Oral Diabetic Therapy in Insulin-Treated Patients with Non-Insulin-Dependent Diabetes Mellitus

Abstract

To test the feasibility of reimplementation of oral diabetic therapy in insulin-treated patients with non-insulin-dependent diabetes mellitus (NIDDM) and to determine the characteristics of patients in whom such conversion was successful. We attempted reinitiation of combination oral therapy with metformin and a sulfonylurea in 55 consecutive C-peptide-positive patients who had had NIDDM for less than 30 years and had received insulin therapy for less than 10 years. Reinitiation of oral therapy was successful in 42 patients and unsuccessful in 13. Reinitiation of oral therapy was unsuccessful because of lack of diabetic control in nine patients and gastrointestinal side effects in four patients. The successful group had a lower insulin requirement (P = 0.004), a shorter duration of insulin therapy (P = 0.013), and a lower body mass index (P = 0.014). Baseline glycosylated hemoglobin, C-peptide level, age, and duration of diabetes were not significant predictive factors. Glycosylated hemoglobin levels were significantly lower (mean, 1.3%; P = 0.0001) after successful reinitiation of oral therapy in comparison with before. Both groups of patients (those with successful and those with unsuccessful conversion to oral therapy) lost weight. The group of patients with NIDDM in whom reinitiation of combination oral therapy is most likely to be successful are those with a shorter duration of insulin therapy, lower insulin requirements, and lower body mass index. Successful conversion to oral diabetic therapy significantly decreases the glycosylated hemoglobin level.