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 A1(c), and 1-year mean haemoglobin A1(c)) was evaluated. The mean urinary level of pyrraline in diabetic patients with poor glycaemic control (HbA(1c)>9.5%) was higher than that in healthy subjects (1.12 +/- 0.35 vs. 0.75 +/- 0.2 mu mol mmol(-1) creatinine, P<0.04), whereas in patients with good to moderate glycaemic control (HbA(1c)<9.5) it was slightly but not significantly higher than in healthy subjects (0.80 +/- 0.3 mu mol mmol(-1) creatinine vs. 0.75 +/- 0.2 mu mol mmol(-1) creatinine). There is a significant correlation between urinary pyrraline level and glycaemia (P<0.008), haemoglobin A1(c) (P<0.01) and 1-year mean haemoglobin A1(c) 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.