Enables glycerol-3-phosphate dehydrogenase [NAD+] activity. Involved in NADH metabolic process and glycerol-3-phosphate metabolic process. Predicted to be part of glycerol-3-phosphate dehydrogenase complex. Predicted to be active in mitochondrion. Human ortholog(s) of this gene implicated in type 2 diabetes mellitus. Orthologous to human GPD2 (glycerol-3-phosphate dehydrogenase 2). [provided by Alliance of Genome Resources, Apr 2022]