Riboflavin increases serum glutamine levels in rats with streptozotocin-induced diabetes

Diabetes mellitus is one of the most common chronic diseases in the world. Metabolomic studies have demonstrated altered blood levels of glutamate and glutamine during type 1 diabetes and type 2 diabetes. Riboflavin is a precursor of flavin adenine dinucleotide and flavin mononucleotide, which are coenzymes necessary for the function of enzymes involved in various biochemical reactions, including those affecting amino acid metabolism. In this study, we investigated the effects of riboflavin on serum glutamate and glutamine levels in rats with streptozotocin-induced type 1 diabetes. Diabetic rats received riboflavin (25 mg, 50 mg, or 100 mg) dissolved in the drinking water daily for 2 weeks. Our results showed that riboflavin supplementation did not affect serum glutamate levels but increased serum glutamine levels in diabetic rats. We speculate that increased serum glutamine levels resulting from riboflavin supplementation may have beneficial effects during diabetes.