Glycine betaine excretion is not directly linked to plasma glucose concentrations in hyperglycaemia

Diabetes mellitus subjects, type 1 and type 2, have increased glycine betai ne excretion compared to normal subjects that correlated with plasma glucos e and HbA(1C) concentrations. The current study was undertaken to determine whether elevated glucose concentration directly increases glycine betaine excretion in an animal model. Non-pregnant female Coopworth sheep received an intravenous glucose load (12.5, 25 and 50% w/v; rate 200 ml/h) for 6 h f ollowed by a 12 h physiological saline washout (0.9% w/v). Plasma and urine samples were analyzed for glycine betaine and glucose. Urine volumes and o smolality were also measured. Using the non-parametric Kruskal Wallis analy sis of variance test we found no difference in glycine betaine excretion be tween glucose loaded and saline infused control animals (P = 0.861). Howeve r, a significant negative correlation (r = -0.28, P < 0.001) was observed b etween urine osmolality and glycine betaine excretion independent of treatm ent. We conclude that acute elevations of plasma glucose concentrations did not result in increased glycine betaine excretion and is therefore unlikel y to be directly responsible for elevated glycine betaine excretion observe d in diabetes mellitus subjects. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.