Diabetes, hyperglycemia, and central corneal thickness - The Singapore Malay Eye Study

Purpose: To examine the relationship of diabetes and hyperglycemia with central corneal thickness (CCT) in Malay adults in Singapore. Design: Population-based cross-sectional study. Participants: Three thousand two hundred eighty Malay adults ages 40-80 years living in Singapore. Methods: The study population was selected using an age-stratified random sampling procedure of Malay 40- to 80-year-olds living in the southwestern part of Singapore. Participants had a standardized interview, examination, and ocular imaging at a centralized study clinic. Central corneal thickness was measured with an ultrasound pachymeter, and nonfasting serum glucose and glycosylated hemoglobin (Hb A(1C)) was obtained from all participants. Diabetes was defined as having nonfasting glucose levels of >= 200 mg/dl (11.1 mmol/l), a self-report of diabetic medication use, or physician diagnosis of diabetes. Main Outcome Measures: Central corneal thickness. Results: Of the 3280 (78.7% response) participants, data on CCT were available on 3239 right eyes. Central corneal thickness was normally distributed, with a mean of 541.2 mu m. There were 748 persons with diabetes (23.0%). After controlling for age and gender, central corneas were significantly thicker in persons with diabetes than in those without diabetes (547.2 mu m vs. 539.3 mu m, P<0.001) and, in the total population, with higher serum glucose (539.6, 540.2, 541.3, and 544.4, comparing increasing glucose quartiles; P = 0.023) and higher Hb A(1C) (537.8, 541.0, 541.4, and 545.5, comparing increasing Hb A(1C) quartiles; P<0.001) levels. In multiple linear regression models adjusting for age, intraocular pressure (IOP), body mass index, and axial length, persons with diabetes had, on average, central corneas 6.50 mu m thicker than those of persons without diabetes. Conclusions: This population-based study among Malays showed that diabetes and hyperglycemia are associated with thicker central corneas, independent of age and IOP levels. These findings may have implications for understanding the relationship between diabetes and glaucoma.