Mannose, Mannitol, Fructose and 1,5-anhydroglucitol Concentrations Measured by Gas Chromatography/mass Spectrometry in Blood Plasma of Diabetic Patients

Gas chromatography/mass fragmentography was applied to measure sugars in the plasma of patients with diabetes mellitus (DM). The isotope-dilution technique was used in the calculation of 1,5-anhydro-D-glucitol (1,5-AG), whereas reductive deuterization of the samples and regression analysis of the reduction products were used to calculate the concentrations of mannose, fructose and mannitol. The concentrations of mannose and glucose were closely and positively correlated both in insulin-dependent (IDDM; r = 0.74, P = 0.001) and non-insulin-dependent (NIDDM; r = 0.89, P = 0.001) DM. The close correlation was also encountered in serial samples taken from patients with widely fluctuating plasma glucose concentrations. The mannose/glucose ratio was increased in NIDDM (P = 0.007). The concentration of 1,5-AG was decreased in both types of DM, but more markedly in IDDM. The concentration was negatively correlated with glucose concentration (r = 0.071, P = 0.02) and HbAtc (r = 0.84, P = 0.001) in NIDDM. It was postulated that both mannose and glucose, by competing with 1,5-AG of renal tubular sugar carrier sites, contribute to the high urinary excretion of 1,5-anhydroglucitol leading to depletion of the sugar in the diabetic organism. The high concentrations of circulating mannose suggested further that the contribution of mannose to the adverse effects of hyperglycaemia should be examined. The study demonstrated that parallel use of the isotope-dilution and reductive deuterization techniques is quite useful in the analysis of monosaccharides in biological fluids.