Fasting blood glucose, erythrocyte counts hemoglobin levels of 131 Libyan diabetic women of Tripoli , Libya were determined. The respective mean values were 223 +/- 7 mg X dl-1, 4.97 +/- 0.034 X 10(6) X mm-3 and 14.4 +/- 0.127 g X dl-1. Sixty-five percent of these diabetic women were obese. The highest percent of diabetics belong to the age group 46-55 years. The increase in prevalence of diabetes correlates with an increase in obesity. A significant positive correlation was found between body surface area and fasting blood glucose levels (r = 0.65; P less than 0.001). Elevated levels of erythrocyte count and hemoglobin were present in these diabetic patients. Significant correlations were found between body surface area and erythrocyte count, as well as between fasting blood glucose levels and erythrocyte count, indicating the effect of obesity and diabetes on erythrocyte numbers. A significant correlation was found between fasting blood glucose levels and hemoglobin (r = 0.35; P less than 0.001). The elevated levels of hemoglobin present in these patients may be the result of haemoconcentration due to polyuria, which is always present in poorly controlled diabetic patients. The results suggest a close relationship between diabetes and obesity. Regulation of body weight/surface area is an important factor in the control of diabetes. The elevated levels of erythrocyte count and hemoglobin reflect poor control of blood glucose levels in these diabetic patients.