Objectives: To identify the fasting glucose/leptin ratio as a new simple method for the detection of insulin resistance in Iraqi diabetes mellitus patients, and to examine its usefulness as a new marker for insulin resistance.Methods: A case control study conducted at the National Diabetes Center, College of Medicine at Al-Mustansiryia University from 1 August 2008 to 30 January 2010. An enzyme spectrophotometric method was used to determine fasting glucose, while HPLC Technique determined leptin and insulin hormones in serum of patients with diabetes mellitus (n=61) and normal healthy subjects as controls (n=63).Results: A positive significant correlation with linear regression equations were found between fasting insulin and fasting leptin hormones, and fasting glucose/insulin and fasting glucose/leptin ratios among the diabetic patient group. While negative, significant correlations were found with linear regression equations between fasting insulin and fasting glucose/insulin ratio, and fasting insulin and fasting glucose/leptin ratio in patients group. Glucopse/leptin ratio had a higher sensitivity compared to glucose/insulin ratio, Quantitative Insulin-Sensitivity Check Index and Homeostasis Model Assessment indexes.Conclusion: Overall, the glucose/leptin ratio can be used in addition to glucose/insulin ratio, Quantitative Insulin-Sensitivity Check Index, and Homeostasis Model Assessment to accurately assess insulin resistance in subjects with hyperglycemia.