Diabetic patients seem to have problems with dry eye symptoms. Therefore, 92 patients with diabetes types I and II and aged from 7 to 69 years were compared with a group of normal healthy controls comparable in number, age and sex. A general ophthalmological check-up was performed. The main points of comparison were subjective complaints, objective findings on conjunctiva and cornea, break-up time (BUT), basal secretion test, impression cytology of the conjunctiva, and grade of diabetic retinopathy. The results show that 52.8% of all diabetic subjects complained of dry eye symptoms, as against 9.3% of the controls. A BUT value lower than 10 s was found in 94.2% of the diabetics and in only 5.8% of the controls. Basal secretion test lower than 5 mm was observed in 26% of the diabetics and in 16% of the normal controls. Pathologic conjunctival epithelium (grade III-V after Tseng) was found in 86% of the diabetic patients and in 6.7% of the healthy subjects. Among the type II diabetic patients, 70% had proven dry eye syndrome, while 57% with type I diabetes suffered from this. A correlation was found between the HBA1c values and the presence of dry eye syndrome. The higher the HBA1c values, the higher the rate of dry eye syndrome. The study thus supports the impression that diabetic patients have an elevated incidence of dry eye syndrome. Impression cytology was found to give the most distinctive and discriminating results. Close monitoring of diabetic patients and good blood sugar regulation is important for the prevention of dry eye syndrome and retinopathy.