A Cochrane review [Abstract] 1 included 25 studies with a total of 12 864 subjects. 11 studies evaluated sitagliptin and 14 studies vildagliptin treatment; study duration ranged from 12 to 52 weeks. No data were published on mortality, diabetic complications, costs of treatment and health-related quality of life. Sitagliptin and vildagliptin therapy in comparison with placebo resulted in an HbA1c reduction of approximately 0.7% (95% CI -0.8 to -0.6) and 0.6% (95% CI -0.7 to -0.5), respectively. Data on comparisons with active comparators were limited but indicated no improved metabolic control following DPP-4 intervention in contrast to other hypoglycaemic agents. Due to pronounced heterogeneity, effects of sitagliptin combined with other antidiabetic agents compared with combinations of other hypoglycaemic drugs are difficult to interpret but DPP-4 inhibitors might provide additional improvement in metabolic control.
Sitagliptin and vildagliptin therapy did not result in weight gain but weight loss was more pronounced following placebo interventions. No definite conclusions could be drawn from published data on sitagliptin and vildagliptin effects on measurements of beta-cell function. Overall, sitagliptin and vildagliptin were well tolerated, no severe hypoglycaemia was reported in patients taking sitagliptin or vildagliptin. All-cause infections increased significantly after sitagliptin treatment (RR 1.15, 95% CI 1.02 to 1.31) but did not reach statistical significance following vildagliptin therapy (RR 1.04, 95% CI 0.87 to 1.24). Studies with sitagliptin and vildagliptin only reported routine laboratory safety measurements.
Comment: The quality of evidence is downgraded by indirectness (lack of important patient oriented outcomes).
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