Renal function in a large cohort of metformin treated patients with type 2 diabetes mellitus

Abstract

Objectives

To survey renal function in a defined population on metformin treatment.

Methods

All patients in the city of Malmö who collected at least three prescriptions of metformin during two years were identified from a central registry at the National Board of Health and Welfare in Sweden. Estimated glomerular filtration rate (eGFR), from the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula, of 5,408 patients were compared with a control population (n=2,815) from the same town. All cases of severe lactic acidosis leading to intensive care unit admission were also sought.

Results

In patients >79 years of age, 38% and 12% of patients had a best recorded eGFR registered below 60 and 45 ml/min/1.73 m² respectively. In the age group 70–79 years the corresponding figures were 16% and 3% respectively. The eGFR was significantly higher in metformin treated patients than in control subjects in each age group. Three cases of lactic acidosis were recorded during the 2-year period studied. No patient with lactic acidosis was found in the highest age group.

Conclusions

In spite of reduced and fluctuating GFR in elderly patients, treatment with metformin is feasible. Adjusting the dose of metformin to renal function and adequately informing the patient could enable continuous treatment in moderately reduced GFR.