Background: Serum concentrations of electrolytes have been shown to change with plasma glucose levels. Magnesium, the second most abundant intracellular cation plays a key role in cellular metabolism. The level of glycemic control is found to be inversely proportional to magnesium deficiency.
 Objectives: To assess the changes in serum magnesium level between T2DM and non-diabetic patients presented with acute myocardial infarction.
 Material & Methods: This cross sectional research was carried out at cardiac care centre of teaching hospital of Lahore from June to December 2020. In this study overall 200 T2DM and non-diabetic patients aged 20-60 years of either gender were inducted via non probability sampling technique. These patients were presented in emergency with acute myocardial infarction within 12 hours from the beginning of symptoms determined by history and medical records. Serum magnesium level between two groups was compared by t-test. The difference was considered significant with p value <0.05.
 Results: The mean age among study participants was 52.72±6.24 years. The majority 70% of the participants were male while 30% were female. Group A comprised of 110(55%) type 2 diabetic patients while group B comprised of 90(45%) non diabetic patients with acute myocardial infarction. Mean serum magnesium level of the study participants was 1.56±0.42 mg/dl. Mean serum magnesium level in group A was 1.25-0.42 mg/dl and in group B was 1.84-0.32 mg/dl. Mean serum magnesium level was significantly lowered in group A (diabetics) as compared to group B (non-diabetics) with p-value=0.000. Study found that low serum magnesium level showed significant association with age, gender, glycemic control and diabetes duration with p-value=0.000. 
 Conclusion: In comparison with non-diabetic patients, serum magnesium level was significantly lowered in diabetic patients presented with acute myocardial infarction. Hypomagnesaemia was directly related to age, gender, glycemic control and duration of diabetes.
 Keywords: Magnesium level, T2DM, Acute Myocardial Infarction, Glycemic control