BACKGROUND: Pinitol(3-O-methyl-D-chiro-inositol) has been identified in putative insulin mediator fractions possessing hypoglycemic activity, and appears to act downstream in the insulin-signaling pathway to mimic the effects of insulin. We evaluated the effect of pinitol therapy in type 2 diabetic patients who were poorly controlled with hypoglycemic drugs such as sulfonylurea, metformin and/or insulin. METHODS: Twenty type 2 diabetic patients were enrolled in this our study. The fasting glucose and c-peptide, total cholesterol, triglyceride, HDL-and LDL-cholesterols were checked before and after treatment with 20mg.kg(-1).day(-1) pinitol for twelve weeks. All subjects continued their current medications during the study. Adipocytokines, such as adiponectin, leptin, free fatty acid and CRP, were checked before and after the pinitol treatment. RESULTS: After the pinitol treatment, the fasting and post-prandial glucose levels and hemoglobin A1c were significantly decreased(P<0.05). The fasting serum adiponectin, leptin, free fatty acid and CRP levels remained unchanged after the pinitol treatment. In the non-responder groups, the serum c-peptide levels were higher than those in the responder groups. CONCLUSION: Twelve weeks of pinitol treatment altered glucose metabolism, but not the lipid profiles or adipocytokine levels. Additional research will be required are needed to define the physiological and potential therapeutic effects of pinitol.