Do type 2 diabetes patients without diabetic retinopathy or subjects with impaired fasting glucose have impaired colour vision? The Okubo Color Study Report

Aims To investigate associations between fasting plasma glucose level and the prevalence of acquired colour vision impairment in type 2 diabetes patients without diabetic retinopathy. Methods Participants in this cross-sectional study of male officials aged 20-60 yr in the Japanese Self Defence Force, underwent colour vision testing, ophthalmic examination, a standardized interview and examination of venous blood samples. Ishihara plates, a Lanthony 15-hue desaturated panel and Standard Pseudoisochromatic Plates Part 2 were used to examine colour vision. The Farnsworth-Munsell 100-hue test was performed to define acquired colour vision impairment. Cardiovascular disease risk factors were determined from serum blood samples, physical records and an interview. We performed logistic regression analysis adjusted for age, diagnosed hypertension, dyslipidaemia, cataract, glaucoma, being overweight, smoking status and alcohol intake. Crude and adjusted odds ratios were calculated for three glucose levels, which included normal fasting glucose, impaired fasting glucose and diabetes. Results Out of a total of 1042 men enrolled, 872 were eligible for the study, and 31 were diagnosed with acquired colour vision impairment. As compared with the subjects with normal fasting glucose (< 5.6 mmol/l), the crude odds ratio for acquired colour vision impairment was 0.93 ( 95% CI 0.32-2.74) for the subjects with impaired fasting glucose ( 5.6-6.9 mmol/l) and 8.07 ( 95% CI 2.48-26.22) for the patients with type 2 diabetes. Themultiple-adjusted odds ratios were 0.77 ( 95% CI 0.25-2.34) for the subjects with impaired fasting glucose and 5.89 ( 95% CI 1.55-22.40) for the patients with type 2 diabetes.