To investigate the differences in ocular biometric and keratometric characteristics in comparison with biometric measurements using the noncontact optical low coherence reflectometer (OLCR) (Lenstar LS 900, Haag-Streit) on diabetic patients. The eyes of 170 patients were included in this study, including 81 diabetic and 89 nondiabetic subjects. Optical biometric measurements of diabetic and nondiabetic patients (between the ages of 25 and 85 years) who applied to the ophthalmology clinic were noted from March to June 2013. Detailed ophthalmologic examinations were done for every subject. Biometric measurements were done using the noncontact OLCR device. Patient age ranged from 29 to 83 years. Subgroup analyses were done in diabetic patients according to their Hba1C levels. The minimum Hba1C value was 5.3, maximum was 12.4, and mean was 7.56 ± 1.48. The median duration of diabetes was 5 years (25th-75th percentile 3.00-11.75). Diabetic patients were found to have thicker lens and shallower anterior chamber in both eyes compared to nondiabetic control subjects. There were no statistical differences between the groups according to central corneal thickness, axial length, or keratometric values in both eyes. However, lens thicknesses were found to be thicker and anterior chamber depth values were found to be shallower in the diabetic group in both eyes. It may useful to determine eyeglasses prescription, refractive surgery calculation, lens selection, and previous cataract surgery according to biometric measurements after the regulation of blood glucose.