Type 2 diabetes treatment and progression of chronic kidney disease in Italian family practice

Aims: Progressive chronic kidney disease represents a dreadful complication of type 2 diabetes mellitus (T2DM). We tested the pattern of use and the renal effects of old glucose-lowering drugs in T2DM patients cared for by Italian general practitioners (GPs). Methods: Data of 2606 T2DM patients were extracted from the databases of GPs, who do not have access to the most recent glucose-lowering drugs in Italy. The rate of kidney function decline was calculated by CKD-EPI, based on two consecutive creatinine values. Results: Metformin was used in 55% of cases, either alone or with sulfonylureas/repaglinide, across the whole spectrum of CKD (from 66% in stage G1 to only 8% in G4). Sulfonylurea use peaked at 21–22% in stage G2–G3a, whereas repaglinide use significantly increased from 8% in G1 to 22% in G4. The median rate of CKD decline was − 1.64 mL/min/1.73 m per year; it was higher in G1 (− 3.22 per year) and progressively lower with CKD severity. 826 cases (31.7%) were classified as fast progressors (eGFR decline more negative than − 5 mL/min/1.73 m per year). The risk of fast progressing CKD was associated with increasing BMI, albuminuria, and sulfonylurea use, alone (OR, 1.47; 95% confidence interval, 1.16–1.85), or in association with metformin (OR, 1.40; 95% CI 1.04–1.88). No associations were demonstrated for metformin, cardiovascular and lipid lowering drug use. Conclusion: In the setting of Italian family practice, sulfonylurea use is associated with progressive CKD in patients with T2DM. Metformin, at doses progressively reduced according to CKD stages, as recommended by guidelines, is not associated with fast progression.