Diabetes mellitus (DM) is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action or both. Endothelial dysfunction is a major factor contributing to morbidity and mortality in diabetes mellitus. The objective of this work was to study the effect of exogenous L-Arginine supplementation on tetrahydrobiopterin (BH4) availability for nitric oxide (NO) generation in normal or diabetic rats and to clarify the role of increases synthesis of NO, a major regulator of glucose utilization by skeletal muscle, in improving glucose...