Risk factors for development of impaired renal function in Type 2 diabetes mellitus patients in primary care

Aims: To evaluate risk factors for the development of an impaired renal function, defined as a glomerular filtration rate (GFR) by Cockcroft-Gault formula < 50.5 ml/min, in primary care patients with Type 2 diabetes mellitus. Methods: A case-control study of Type 2 diabetes mellitus patients with impaired renal function and age, sex and practice matched controls with Type 2 diabetes mellitus without impaired renal function in 10 Dutch family practices performing the Nijmegen Monitoring Project. Main outcome measure was the independent risk factors of impaired renal function. Results: Eighty-seven individuals with impaired renal function were identified. The point prevalence of impaired renal function in the sample population on 31 March 2001 was 87/873 (10.0%; 95% confidence interval 7.0-15.1%). Of 87 cases, 23 (26.5%; 17.3-30.9%) were found to have impaired renal function at diagnosis. Conditional multiple logistic regression analysis revealed the following independent risk factors for the development of impaired renal function: duration of diabetes ≥ 8 years (adjusted odds ratio 5.6 (2.5-12.5); P < 0.001), glomerular filtration rate by Cockcroft-Gault formula 50.5-80.5 ml/min at diagnosis [3.5 (1.5-8.1); P < 0.01] and existing macrovascular complications at diagnosis [2.6 (1.1-6.3); P < 0.01]. Conclusion: Duration of diabetes ≥ 8 years, mild renal impairment at the time of diagnosis and existing macrovascular complications at the time of diagnosis are independent risk factors for the development of impaired renal function in white patients with Type 2 diabetes mellitus.