ABSTRACT
BACKGROUND: Recently, the usefulness of metformin as an oral hypoglycemic agent has been re-evaluated, while secondary failure of long-term treatment with sulfonylurea (SU) has become a serious problem. In this study, the usefulness of combination therapy with metformin was evaluated in patient with non-obese type 2 diabetes mellitus showing secondary failure of treatment with SU.<BR>PATIENTS AND METHODS: Twenty non-obese patients with type 2 diabetes mellitus showed HbA<SUB>1c</SUB> levels of 7% or over despite more than 5 years of treatment with SU. Metformin was administered to these patients at a dose of 500 mg/day for 3 months in combination with SU, and glycemic control was compared before and after combination therapy.<BR>RESULTS: After combination therapy, the mean plasma glucose level obtained 2 hours postprandial was significantly decreased by 20.0% (216±41.7 mg/dl vs. 172.0±47.7 mg/dl, p<0.001) . In addition, the mean HbA<SUB>1c</SUB> level was significantly decreased by 8.8% (8.0±0.8% vs. 7.3±0.8%, p<0.001) . However, the mean IRI level, the mean body mass index, and mean plasma lipid levels did not significantly change after combination therapy.<BR>CONCLUSIONS: These findings suggest that combination therapy with metformin is useful for improving blood glucose levels without enhancing insulin secretion in patients with non-obese type 2 diabetes mellitus who showed secondary failure of treatment with SU. However, further studies are needed to confirm whether this combination therapy will contribute to delaying the introduction of insulin therapy.