Serum lactate levels are associated with serum alanine aminotransferase and total bilirubin levels in patients with type 2 diabetes mellitus: A cross-sectional study

•We analyzed to evaluate the significance of serum lactate elevation in T2DM.•ALT and total bilirubin were associated with serum lactate levels.•The lactate levels were higher in patients with ALT-predominant liver dysfunction.•Serum lactate may serve as a biomarker of liver dysfunction. It was recently reported that lactate acts as a metabolic mediator and rises in the diabetic state, but the physiological effects are as yet poorly understood. The objective of the current study was to evaluate the significance of serum lactate elevation in type 2 diabetes mellitus (T2DM) patients. Fasting serum lactate levels, hematological and inflammatory serum markers and anthropometric parameters, obtained employing bioelectric impedance analysis, were measured in 103 patients with T2DM. Statistically significant correlations of serum lactate levels with C-reactive peptide, insulin, aspartate aminotransferase, alanine aminotransferase (ALT), serum lipids, total bilirubin, adiponectin, homeostasis model assessment-insulin resistance, body weight, body mass index and body fat (weight or percentage of subcutaneous fat, visceral fat or total body fat), but neither fasting plasma glucose nor HbA1c, were detected. Stepwise regression analysis showed ALT to be independently positively associated with total bilirubin, while being negatively associated with serum lactate levels. Furthermore, serum lactate levels were significantly higher in patients with ALT-predominant liver dysfunction. We found fasting serum lactate elevation in T2DM patients to be associated with the serum levels of ALT and total bilirubin independently of blood glucose control. Trial registration: UMIN clinical trials registry (UMIN000029178).