Background: High-altitude-induced hypoxia results in various diseases, such as chronic mountain sickness and high altitude retinal edema, and may affect severity and incidence of some cardiovascular diseases. In order to evaluate the effects of moderately high altitude on diabetic nephropathy and retinopathy, a cross-sectional study was planned. Material Method: Long-term type II diabetic residents of sea level (n = 75, 38 male, 37 female, mean age 51.9 +/- 10.5 in Trabzon and Zonguldak cities) and moderately high altitude (h = 1,727 m, n = 73, 28 male, 45 female, mean age 48.3 +/- 12.1, Van city) were compared. Results: No difference was observed in terms of age, gender, diabetes duration, body mass index, smoking, systolic, diastolic, and mean arterial blood pressure values, serum glucose levels, cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, hemoglobin, HbAlC, hypertension control, or blood pressure medications and retinopathy incidence. Mean 24 h protein excretion (210.0 +/- 139.9, 127.8 +/- 112.1 mg: P = 0.00). proteinuria prevalence (57.5% versus 33.3%, p = 0.003), and serum creatinine levels (1.04 +/- 0.22 versus 0.84 +/- 0.21,p = 0.00) were significantly higher in the highlanders, glomerular filtration rate (GFR) was significantly lower in sea level (SL) patients (90.9 +/- 26.5 versus 83 +/- 21.1: p = 0.05). Conclusion: Tendency to diabetic nephropathy as indicated by higher proteinuria and creatinine levels is increased among type 2 diabetic patients living at moderately high altitude. Prospective studies are needed to confirm these findings.