When to perform renal biopsy in patients with type 2 diabetes mellitus? Predictive model of non-diabetic renal disease

Abstract

IntroductionDiabetic nephropathy (DN) is one of the most frequent complications in patients with diabetes mellitus (DM) and its diagnosis is usually established on clinical grounds. However, kidney involvement in some diabetic patients can be due to other causes, and renal biopsy might be needed to exclude them. The aim of our study was to establish the clinical and analytical data that predict DN and no-diabetic renal disease (NDRD), and to develop a predictive model (score) to confirm or dismiss DN. Material and methodsWe conducted a transversal, observational and retrospective study, including renal biopsies performed in type 2 DM patients, between 2000 and 2018. ResultsTwo hundred seven DM patients were included in our study. The mean age was 64.5±10.6 years and 74% were male. DN was found in 126 (61%) of the biopsies and NDRD in 81 (39%). Diabetic retinopathy was presented in 58% of DN patients, but only in 6% of NDRD patients (p<0.001). Patients with NDRD were diagnosed of primary glomerulopathies (52%), nephroangiosclerosis (16%), inmunoallergic interstitial nephritis (15%) and vasculitis (8.5%). In the multivariate analysis, retinopathy (OR 26.7; 95% CI: 6.8–104.5), chronic ischemia of lower limbs (OR 4.37; 95% CI: 1.33–14.3), insulin therapy (OR 3.05; 95% CI: 1.13–8.25), time course of DM ≥10 years (OR 2.71; 95% CI: 1.1–6.62) and nephrotic range proteinuria (OR 2.91; 95% CI: 1.2–7.1) were independent predictors for DN. Microhaematuria defined as ≥10 red blood cells per high-power field (OR 0.032; 95% CI: 0.01–0.11) and overweight (OR 0.21; 95% CI: 0.08–0.5) were independent predictors of NDRD. According to the predictive model based on the multivariate analysis, all patients with a score >3 had DN and 94% of cases with a score ≤1 had NDRD (score ranked from −6 to 8 points). ConclusionsNDRD is common in DM patients (39%), being primary glomerulonephritis the most frequent ethology. The absence of retinopathy and the presence of microhematuria are highly suggestive of NDRD. The use of our predictive model could facilitate the indication of performing a renal biopsy in DM patients.