Lactate levels and risk of lactic acidosis with metformin in diabetic kidney disease patients

Metformin as an oral antidiabetic drug (OAD) is not recommended in renal failure due to the presumed risk of lactic acidosis though it has advantages in cardiovascular protection with a low risk of hypoglycemia. Few studies have measured lactic acid blood levels in patients with diabetic kidney disease on metformin and demonstrated lactic acidosis. The aim of our study is to see if patients with diabetic kidney disease are at risk of elevated lactate blood levels and lactic acidosis. Lactate levels and blood pH were estimated in patients with type 2 diabetes mellitus receiving metformin in different stages of chronic kidney disease (CKD) and were compared with a similar group not receiving metformin. Patients with diabetic kidney disease, with estimated glomerular filtration rate <60 mL/min who were previously receiving metformin started in centers elsewhere and referred here were studied and compared with a similar group taking other OADs or insulin. Independent sample t-test or ANOVA were used to compare quantitative variables between groups. Pearson correlation was used to analyze association between quantitative variables and linear regression analysis and was employed to note the relationship between quantitative variables. Of 57 patients who received a mean dose of 1.134 grams of metformin, 33 (55.9%) were in stage 3, 16 (28.1%) in stage 4, and 8 (14%) in stage 5 CKD. Mean serum pH (P = 0.572), bicarbonate (P = 0.978), and plasma lactate (P = 0.449) levels in those taking and not taking metformin were comparable. There was no difference in the plasma lactate levels in different stages of CKD in the metformin group (P = 0.498) although there was significant correlation with metformin dose (P <0.05). Blood lactate levels were not elevated in patients with diabetic kidney disease at a daily dose of metformin <1 g.