Aim: Our aims are to discover the average fasting plasma lactate level (FPL) in Asian patients with type 2 diabetes mellitus on metformin, with or without renal impairment and whether FPL is associated with the total daily dose of metformin (Tmet) and the degree of renal impairment in these patients.

Methods: We conducted an observational cross-sectional study of Asian patients with type 2 diabetes, using measurements of FPL levels and glomerular filtration rate (GFR) calculated, using the abbreviated modification of diet in renal disease (MDRD) formula. The association between FPL, Tmet, GFR and other potential predictors was analysed.

Results: A total of 97 subjects were recruited from our diabetes centre between July 2005 and February 2006. Sixty (61.9%) of the subjects were males; 69 (71.1%) Chinese, 21 (21.6%) Malays and 6 (6.2%) Indians. The mean (SD) age was 58.8 years (10.7) and the mean body mass index was 27.1 kg/m(2) (5.3). The mean FPL was 1.8 mmol/l (0.9) with 20 (20.6%) of subjects having an FPL beyond the upper limit of our reference range of 2.2 mmol/l. The mean FPL (two SE) of subjects with Tmet of < or = 1000, 1001-2000 and > 2000 mg were 1.7 mmol/l (0.2), 1.6 mmol/l (0.2) and 2.1 mmol/l (0.5) respectively, (p = 0.119). The mean FPL of subjects with GFR of < 60, 60-90 and > 90 ml/min/1.73 m(2) was 1.7 mmol/l (0.3), 1.8 mmol/l (0.3) and 1.8 mmol/l (0.4) respectively, p = 0.757. Among the potential predictors analysed, aspartate transaminase (p = 0.001) was found to be significantly associated with FPL.

Conclusions: Our study shows no correlation between Tmet and GFR with FPL in Asian type 2 diabetic patients on metformin.