Abstract: Objective To observe the effect of oral magnesium supplement on expression of insulin receptor in elderly rats with type 2 diabetes mellitus(DM). Methods Elderly rats with type 2 DM were divided into different oral magnesium dose supplement groups.Fasting glucose,serum insulin,and insulin receptor expression levels in pancreas and skeletal muscles were measured. Results The expression level of insulin receptor increased from 0.331±0.003 to 0.342±0.002 and from 0.345±0.003 to 0.355±0.002,respectively,while the fasting glucose and serum insulin levels decreased from 16.85±0.76mmol/L to 15.49±0.57mmol/L and from 20.35±0.52μIU/ml to 19.05±0.62μIU/ml,respectively,in pancreas and skeletal muscles of the high dose(2g/kg) oral magnesium dose group(P<0.05). Conclusion Oral magnesium supplement can significantly increase the expression level of insulin receptor and improve the insulin sensitivity in elderly rats with type 2 DM.