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 JDM  Vol.4 No.1 , February 2014
Improved β-cell function rather than increased insulin sensitivity is associated with reduction in hemoglobin A1c in newly diagnosed Type 2 diabetic patients treated with metformin
Abstract: β-cell dysfunction and decreased insulin sensitivity are believed to be two chief mechanisms that participate in deterioration of glycemic control in Type 2 diabetes. Meformin is widely accepted as the first-line oral agent in the treatment of Type 2 diabetes. However, the relative contributions of improved β-cell function and increased insulin sensitivity to reduction in hemoglobin A1c (HbA1c) are unclear in newly diagnosed Type 2 diabetic patients treated with metformin. We investigated β-cell function and insulin sensitivity in relation to reduction in HbA1c in 20 newly diagnosed Type 2 diabetic patients (17 men and 3 women, mean age 49.1 ± 10.1 years, mean body mass index 26.4 ± 5.2 kg/m2) treated with metformin for 16 weeks. We used homeostasis model assessment (HOMA) 2%B and HOMA2%S as estimates of β-cell function and insulin sensitivity, respectively. Median HOMA2%B and HOMA2%S significantly increased from 38.8 to 68.8 (p < 0.001) and from 50.2 to 67.1 (p = 0.004), respectively. In univariate regression analysis, reduction in HbA1c was highly correlated with change in HOMA2%B (r = -0.866, p < 0.001), but not with that in HOMA2%S (r = -0.264, p = 0.260). Furthermore, multivariate regression analysis with reduction in HbA1c as a dependent variable showed that increase in HOMA2%B but not that in HOMA2%S was a significant dependent variable (β = -0.847, p < 0.001). In conclusion, our findings demonstrate that improved β-cell function rather than increased insulin sensitivity is associated with reduction in HbA1c. These results suggest that metformin reduces HbA1c chiefly through improved β-cell function rather than increased insulin sensitivity in patients with newly diagnosed Type 2 diabetes.
Cite this paper: Sumitani, S. , Morita, S. , Deguchi, R. , Hirai, K. , Mukai, K. , Utsu, Y. , Miki, S. , Sato, B. , Nakamura, H. and Kasayama, S. (2014) Improved β-cell function rather than increased insulin sensitivity is associated with reduction in hemoglobin A1c in newly diagnosed Type 2 diabetic patients treated with metformin. Journal of Diabetes Mellitus, 4, 44-49. doi: 10.4236/jdm.2014.41008.
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