Lactic acidosis due to metformin in type 2 diabetes mellitus and chronic kidney disease stage 3-5: is it significant?

PURPOSE: To study the incidence of lactic acidosis due to metformin in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) stage 3-5.

METHODS: We estimated plasma lactate in patients of CKD stage 3 and worse who were continuing metformin on their own prior to stopping the drug.

RESULT: Of 40 patients included, median duration of T2DM was 60 months (interquartile range IQR 24-120). The mean serum creatinine was 309.4 ± 159.1 µmol/L and mean eGFR was 27.82 ± 12.93 mL/min/1.73 m2 with 3 (7.5%), 16 (40%), 11 (27.5%) and 10 (25%) in CKD stages 3a, 3b, 4 and 5, respectively. They were receiving metformin for a median duration of 24 months (IQR 12.5-60), an average dose of 896 ± 350 mg per day. The median of plasma lactate was 1.36 mmol/L (IQR 1.11-1.75 mmol/L) with three (7.5%) having levels above normal, two (20%) in CKD stage 5 and one (9.1%) in stage 4.

CONCLUSION: Metformin can be safely used in CKD stage 3 and with regular measurement of plasma lactate in later stages.