Sitagliptin as an Initial Therapy and Differential Regulations of Metabolic Parameters Depending on its Glycemic Response in Subjects with Type 2 Diabetes.

The aim of this study is to investigate whether sitagliptin can be used as an initial drug for T2DM and to evaluate its effects on metabolic parameters in relation to its glycemic efficacies. The subjects received 25-50 mg/day sitagliptin monotherapy (n=69). At 3 months, they were divided into three groups (n=23 each) according to the novel parameter called "A1c index" which is designed to assess glycemic efficacy. The metabolic parameters were compared between good-responders and poor-responders. These two groups acted as a control each other. In the overall subjects, efficient reductions of HbA1c (10.16-8.22%) were observed with few adverse events. Significant correlations were seen between the A1c index and changes of (∆)nonHDL-C (R=0.250) or ∆LDL-C (R=0.368). At baseline, T-C, nonHDL-C and BMI levels were significantly lower in good-responders than poor-responders. At 3 months, in good-responders, HbA1c levels effectively decreased (11.03-7.00%). Indexes for insulin sensitivity/resistance [HOMA-R and 20/(C-peptide x FBG)] and beta-cell function (HOMA-B and CPR-index) ameliorated. T-C, nonHDL-C and LDL-C significantly decreased, while BMI increased. However, in poor-responders, no changes in these parameters were noted. Collectively, these results suggest that 1) Sitagliptin can be used as a first-line drug for T2DM and its glycemic efficacy is linked to some atherogenic lipids. 2) Those with lower T-C, nonHDL-C and BMI appear to respond better with this drug. 3) Good glycemic efficacy of sitagliptin is medicated through reduced insulin resistance as well as enhanced beta-cell functions. Body weight increased, while some atherogenic cholesterol decreased in good-responders.