Diabetes, metformin and lactic acidosis

Authors: Scale, T.; Harvey, J. N.

Source: Clinical Endocrinology, Volume 74, Number 2, February 2011 , pp. 191-196(6)

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Abstract:

Summary Objective

Metformin has long been thought to cause lactic acidosis (LA) but evidence from various sources has led researchers to question a direct causative relationship. We assessed the relationship of metformin prescription and other factors to the incidence of LA. Methods

All cases of LA at a single hospital were identified from laboratory lactate measurements. We compared patients classified as Cohen and Woods class A and B, patients with and without diabetes, and those taking metformin or not. Results

LA was more common than in published analyses based on hospital coding of diagnoses. The incidence of LA was greater in diabetes than in the nondiabetic population but with no further increase in patients taking metformin. Lactate levels were no greater in patients on metformin than in patients with type 2 diabetes not on metformin even if patients with acute cardiorespiratory disturbance (Cohen and Woods class A) were excluded. Acidosis was greater in diabetes (hydrogen ion 94·9 ± 4·6 vs 83·2 ± 2·3 10⁻⁹ m, P = 0·027) but factors besides lactate contributed. Acute cardiorespiratory illness, acute renal impairment and sepsis were the most common of the recognized precipitating factors. Age (P = 0·01), acute renal failure (P = 0·015) and sepsis (P = 0·005) were associated with mortality. Conclusions

Diabetes rather than metformin therapy is the major risk factor for the development of LA. Lactic acidosis occurs in association with acute illness particularly in diabetes. Current guidance for the prevention of lactic acidosis may overemphasize the role of metformin.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2265.2010.03891.x

Publication date: 2011-02-01