AIM: To study the central corneal thickness(CCT)in diabetic patients and its relationship with glycemic control(HbA1c levels).

METHODS: Single-centre, prospective, clinical trial with a mean of 6-month follow-up examination. We included 52 patients with type 2 diabetes mellitus(DM)whose HbA1c levels were above 7%, indicating poor glycemic control. Sex of patients, and duration of DM were recorded. CCT was determined with ultrasound pachymeter. Each CCT measurement was the mean of 3 pachymeter readings. Then the patients were treated by the endocrinology clinic. When glycemic control was achieved(HbA1c≤7%), CCT measurements were recorded again. HbA1c and CCT before and after treatment were compared.

RESULTS: Mean CCT before treatment was 552.30±29.26μm, and mean HbA1c was(9.36±1.79)%. Mean CCT after treatment was 542.36±27.20μm, and mean HbA1c was(6.45±0.70)%. The difference between these two values was statistically significant(P=0.0001, paired t test).

CONCLUSION: Even though mean hyperglycemic and euglycemic CCT measurements were in normal range, CCT decreases significantly by lowering HbA1c level(good glycemic control). Therefore, glycemic status(HbA1c)should be considered when examining the eye of diabetic patients.