Short-term renal and metabolic effects of low dose vildagliptin treatment added-on insulin therapy in non-proteinuric patients with type 2 diabetes: open-label randomized prospective study

Objective: The aim of this randomized comparative study was to assess renal and metabolic effects of vildagliptin in insulin-treated type 2 diabetes (T2DM) patients without overt chronic kidney disease. Subjects and method: We randomized 47 insulin-treated non-proteinuric patients with satisfactory controlled T2DM and estimated glomerular filtration rate (eGFR) >= 60 mUmin/1.73m(2) either to continue insulin therapy (control) or to receive combined insulin-vildagliptin treatment WIG group). We assessed eGFR using serum creatinine (eGFRcreat), cystatin C (eGFRcys), and both (eGFRcreatcys), and urinary creatinine-adjusted excretion of albumin (UACR), type IV collagen (uCol IV/Cr), and neutrophil gelatinase-associated lipocalin (uNGAL/Cr) at baseline and after 6 months of treatment. Results: Study groups were comparable in terms of age and sex (60.1 +/- 6.1 years and 42.9% men in control group vs. 60.8 +/- 5.2 years and 39.1% in VIG group). After 6 months of treatment, there were no significant changes in main assessed parameters in control group. VIG group demonstrated significant decrease in HbA1c, diastolic blood pressure, frequency of hypoglycemia, and high-sensitivity C-reactive protein level as compared to the changes in control group. While eGFRcreat, UACR, and uNGAL/Cr showed no significant changes after vildagliptin addition, eGFRcys, eGFRcreat-cys, and uCol IV/Cr changed significantly in comparison with control group (+7.0% [3.7;13.3]; +5.1% [1.4;8.5]; -32,8% [-55.8;-24.4], respectively, p <0.01 each). Correlation and regression analysis revealed glucose-independent pattern of these changes. Conclusion: Addition of vildagliptin to ongoing insulin therapy in patients withT2DM was associated with a reduction in uCol IV/Cr and an increase in eGFRcys and eGFRcreat-cys, independent ofT2DM control parameters.