Association between Metformin Use and Risk of Lactic Acidosis or Elevated Lactate Concentration in Type 2 Diabetes

PURPOSE

Metformin can reduce diabetes-related complications and mortality. However, its use is limited because of potential lactic acidosis-associated adverse effects, particularly in renal impairment patients. We aimed to investigate the association of metformin use with lactic acidosis and hyperlactatemia in patients with type 2 diabetes.

MATERIALS AND METHODS

This was a cross-sectional study from a tertiary university-affiliated medical center. A total of 1954 type 2 diabetes patients were recruited in 2007-2011, and stratified according to the estimated glomerular filtration rate of 60 mL/min/1.73 m². Lactic acidosis was defined as plasma lactate levels >5 mmol/L and arterial pH <7.35.

RESULTS

Metformin was used in 61.4% of the patients with type 2 diabetes mellitus. Plasma lactate levels were not different in the patients with and without metformin use. There was no difference in prevalence of hyperlactatemia and lactic acidosis between the patients with and without metformin use (18.9% vs. 18.7%, p=0.905 for hyperlactatemia and 2.8% vs. 3.3%, p=0.544 for lactic acidosis). Similar results were observed in the patients with estimated glomerular filtration rate <60 mL/min/1.73 m². Most patients with lactic acidosis had at least one condition related to hypoxia or poor tissue perfusion. Multiple regression analysis indicated no association between metformin use and lactic acidosis, whereas tissue hypoxia was an independent risk factor for lactic acidosis [odds ratio 4.603 (95% confidence interval, 1.327-15.965)].

CONCLUSION

Metformin use was not associated with hyperlactatemia or lactic acidosis in patients with type 2 diabetes.

A Case of Rectal Squamous Cell Carcinoma with Metachronous Diffuse Large B Cell Lymphoma in an HIV-Infected Patient

Diffuse large B cell lymphoma (DLBCL) is one of the most common acquired immune deficiency syndrome (AIDS)-defining malignancies among human immunodeficiency virus-infected patients, and rectal cancer has recently emerged as a prevalent non-AIDS-defining malignancy. We report a case of rectal squamous cell carcinoma that was metachronous with DLBCL in an HIV-infected patient who was receiving highly active antiretroviral therapy. The patient was diagnosed with DLBCL and showed complete remission after chemotherapy. Follow-up imaging showed increased uptake at the rectum, previously treated as lymphoma. Repeated biopsy was performed and squamous cell carcinoma of the rectum was reported. After concurrent chemoradiation therapy, curative resection was performed.