Diabetes Care, Vol 18, Issue 6 779-784, Copyright © 1995 by American Diabetes Association
Role of metformin accumulation in metformin-associated lactic acidosis
JD Lalau, C Lacroix, P Compagnon, B de Cagny, JP Rigaud, G Bleichner, P Chauveau, P Dulbecco, C Guerin, JM Haegy and al. et
Service d'Endocrinologie, Hopital Universitaire, Amiens, France.
OBJECTIVE--To investigate the role of metformin accumulation in the
pathophysiology of metformin-associated lactic acidosis. RESEARCH DESIGN
AND METHODS--We used high-performance liquid chromatography to measure
plasma metformin concentrations in 14 patients who experienced lactic
acidosis (pH < 7.35 and lactate concentration 5 > mmol/l) while
receiving chronic metformin treatment. Their treatment was generally based
on alkalinization and dialysis therapy. RESULTS--Clinical shock and/or
evidence of tissue hypoxia was found in all patients with the exception of
one who had a nonsteroidal anti-inflammatory drug-induced anuria. Ten
patients had significant metformin accumulation (plasma metformin
concentrations 4.1-84.9 mg/l, normal value 0.6 +/- 0.5 mg/l before drug
intake), generally because of failure to withdraw metformin despite
intercurrent pathological conditions affecting its renal elimination (serum
creatinine concentrations ranging from 269 to 1,091 mumol/l). There was no
metformin accumulation (plasma metformin 0.03-0.7 mg/l) in the four other
patients, who had less severe renal failure (serum creatinine 140-349
mumol/l). The severity of the patient's general condition did not predict
early hospital mortality (death before discharge from the intensive care
unit) even in patients in shock. Whereas it was high in those without
metformin accumulation (only 1 of 4 patients recovered), early hospital
mortality was low in the 10 patients with metformin accumulation and was
not related to its extent (3 patients died with end-stage hepatic failure
or cardiac failure). Correlation studies showed a positive correlation
between serum creatinine and plasma metformin and between plasma metformin
and arterial lactate but, for the latter correlation, only in patients with
metformin accumulation. CONCLUSION--Metformin-associated lactic acidosis is
not necessarily due to metformin accumulation; true type B (aerobic) lactic
acidosis, i.e., without an apparent associated hypoxic factor, seems
exceptional. Neither the severity of the clinical picture nor the degree of
metformin accumulation predicted survival; rather, the prognosis was
dependent upon the severity of the associated pathological conditions.