It is important that physicians gain an increased awareness of lactic acidosis as a complication of the use of metformin, said Helga Gudmundsdottir, MD, Department of Nephrology, Ulleval University Hospital, Oslo, Norway.

Concurrent use of ACEI or ARB and metformin has become frequent among patients with type 2 diabetes mellitus, and haemodialysis for patients with metformin-associated lactic acidosus can be life-saving.

Dr. Gudmundsdottir presented data from five patients with type 2 diabetes mellitus and hypertension who developed life-threatening metformin-associated lactic acidosis due to acute renal failure.

The condition in each of the five cases was precipitated by the use of an ACEI or ARB in a setting with dehydration. Metformin-associated lactic acidosis is extremely rare in Norway, and the four women and one man (aged 49-81 years) in this small study all had previously normal renal function. All used metformin in combination with an ACEI or an ARB.

The five patients were admitted to the hospital during a period of 4 months in critical condition with severe metabolic acidosis (pH 6.60-6.94), serum lactate levels between 14 and 23 mmol/L and serum creatinine levels of 796 to 1621 mcmol/L after a few days with acute intercurrent disease causing dehydration.

Within 2 to 3 hours of hospital admittance all developed circulatory and respiratory collapse requiring assisted mechanical ventilation and inotropic support, Dr. Gudmundsdottir noted.

Dr. Gudmundsdottir concluded that withdrawal of the ACEI or ARB during intercurrent illness should be recommended, and haemodialysis should be started without delay in the event that acute renal failure does cause metformin-associated lactic acidosis.

All five patients in this study were treated with either intermittent bicarbonate haemodialysis or continuous haemodiafiltration with bicarbonate buffering. Lactate and metformin were cleared rapidly from plasma during the first hours, and the haemodynamic situation became more stable. All patients, however, needed haemodialysis or continuous haemodiafiltration for an extended period of time, Dr. Gudmundsdottir said.

All patients were eventually discharged from the hospital with normal renal function and without aftereffects, except in one patient who lost his vision.


[Presentation title: Metformin and Drugs Blocking the Renin-Angiotensin-System, a Potential Life-Threatening Combination. Abstract 897]

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