Background: Hypomagnesaemia has been reported to occur with increased frequency in patients with type 2 diabetes mellitus; it is frequently overlooked and undertreated. Hypomagnesemia has also been associated with diabetic retinopathy. Aim of the work: : The present study was conducted with an objective to evaluate the plasma magnesium in type 2 Diabetes mellitus cases. The present study also attempts to evaluate the possible relationship between diabetic retinopathy and plasma magnesium levels. Patients and methods:In this study 50 type 2 diabetic patients with age group of 30 to70 years were included and divided into 3 groups.group I included diabetic patients with PDR,group II included diabetic patients with PDR and group III included diabetic patients without retinopathy.all cases were subjected to estimate biochemical parameters in form of RBS,plasma magnesium level ,HbA1c and kidney function tests ,plus fundus examination. In this study we exclude patients with renal failure,patients with acute myocardial infarction in last six months,patients on diuretics or on magnesium supplementation or magnesium containing antacid ,mala absorption syndrome,chronic diarrhea and patients with history of alchol abuse. Results: The comparative study consists of 9 diabetic patient with proliferative diabetic retinopathy( group I), 21 diabetic patient with non proliferative diabetic retinopathy (groupII) and 20 diabetic patient with out diabetic retinopathy(group III). The average range of plasma Magnesium level among 3 groups was 1.36±0.26, 1.62±0.26 and 1.86±0.20 respectively, There is significant difference among 3 group(P< 0.05), low level of plasma magnesium with group I (proliferative diabetic retinopathy) and high level with group III(with out retinopathy).Conclusion: The serum magnesium levels were significantly lower in patients with diabetic retinopathy compared to diabetics without complications.