Glycaemic control and in vivo non-oxidative Maillard reaction: urinary excretion of pyrraline in diabetes patients.

The presence of pyrraline in human urine has recently been described. Using reversed-phase high-performance liquid chromatography, we measured urinary pyrraline in 45 insulin-treated diabetic patients with preserved renal function and in 30 age- and sex-matched healthy subjects. The relationship between urinary pyrraline and metabolic control parameters in the diabetic population (glycaemia, fructosamine, haemoglobin A1c, and 1-year mean haemoglobin A1c) was evaluated. The mean urinary level of pyrraline in diabetic patients with poor glycaemic control (HbA1c > 9.5%) was higher than that in healthy subjects (1.12 +/- 0.35 vs. 0.75 +/- 0.2 mumol mmol-1 creatinine, P < 0.04), whereas in patients with good to moderate glycaemic control (HbA1c < 9.5) it was slightly but not significantly higher than in healthy subjects (0.80 +/- 0.3 mumol mmol-1 creatinine vs. 0.75 +/- 0.2 mumol mmol-1 creatinine). There is a significant correlation between urinary pyrraline level and glycaemia (P < 0.008), haemoglobin A1c (P < 0.01) and 1-year mean haemoglobin A1c values (P < 0.007), but not with fructosamine. The results of the present work prove, for the first time, that glycaemic status influences circulating levels of advanced Maillard reaction products.