URINARY GLYCOSYLATED, FREE AND TOTAL PYRIDINOLINE AND FREE AND TOTAL DEOXYPYRIDINOLINE IN DIABETES-MELLITUS

OBJECTIVE Published data on bone metabolism in diabetes mellitus are c onflicting, We have measured pyridinium crosslinks, biochemical marker s of bone resorption, in order to evaluate bone resorption in diabetes mellitus. We also wished to investigate whether, as a consequence of chronic hyperglycaemia, pyridinoline is glycosylated to a greater exte nt in patients with diabetes mellitus, DESIGN AND PATIENTS This cross sectional study included 142 patients (64 males, 78 females) with insu lin dependent and non-insulin dependent diabetes mellitus (IDDM and NI DDM). These patients were compared to a healthy control group of 99 in dividuals (39 males and 60 females), MEASUREMENTS Pyridinium crosslink s, glycosylated, free and total pyridinoline (gPYD, fPYD, tPYD) and fr ee and total deoxypyridinoline (fDPD, tDPD) were measured in a spot ur ine sample by high performance liquid chromatography (HPLC). Urinary c reatinine, albumin and glucose were also measured, RESULTS In the diab etic group, values of urinary gPYD and tDPD were significantly lower t han in controls. gPYD excretion was lowest in patients with severe gly cosuria. Free pyridinium crosslinks, both fPYD and fDPD, were excreted to a significantly lower extent, The molar ratio of tPYD to tDPD was significantly increased in diabetes mellitus, CONCLUSIONS Decreased ex cretion of tDPD suggests low bone resorption in IDDM and NIDDM, Pyridi noline is not glycosylated to a greater extent in diabetes mellitus an d tends to be decreased in proportion to the degree of glycosuria. Exc retion of gPYD, fPYD and fDPD is depressed in severe glycosuria. Dimin ished degradation to the final products, fPYD and fDPD, might represen t increased resistance to enzymatic activity or diminished enzymatic a ctivity, The increased molar ratio tPYD/tDPD in urine suggests an incr eased ratio in bone collagen in diabetes mellitus.