Dipeptidyl peptidase-4 activity is associated with urine albumin excretion in type 1 diabetes.

Aims: The inability of kidneys to prevent urinary protein leakage represents the earliest sign of renal damage in diabetic kidney disease (DKD). Recent data suggest the possible nephroprotective role of the dipeptidyl peptidase-4 (DPP-4) inhibitors. We aimed to investigate whether serum DPP-4 activity is associated with urine albumin excretion (UAE) in patients with type 1 diabetes (type 1 DM).

Methods: DPP-4 activity and UAE measurement were performed in 113 patients with type 1 DM and glomerular filtration rate (GFR) within normal range. They were divided into three groups according to UAE tertiles.

Results: Worse lipid profile and higher waist circumference were observed in the group with highest DPP-4 activity. Patients within lowest UAE tertile group had lowest DPP-4 activity value (p<0.001) compared to group within second and third tertile of UAE. DPP-4 activity correlated with systolic blood pressure (ρ=0.142; p=0.001), HbA1c (ρ=0.133; p=0.013) and UAE (ρ=0.349; p<0.001). In the linear regression analysis when DPP-4 activity was adjusted for age, gender, disease duration, HbA1c, waist circumference, the use of ACEI and hypolipemic agents the association remained significant; UAE increased for 8.136mg/24h by each increase of DPP-4 activity of 1U/L (p<0.008).

Conclusion: Our results indicate that serum DPP-4 activity is associated with albuminuria in type 1 diabetes. This arises the question whether the use of DPP-4 inhibitors might serve as an additional therapeutic strategy to prevent proteinuria in patients with DKD.