Positive association of large alcohol intake per occasion with vision-threatening severe diabetic retinopathy or diabetic macular edema in Japanese men with type 2 diabetes

Objective: Differing from the overall consumption of alcohol, whether consuming large quantities of alcohol per drinking occasion is associated with higher risk of developing severe diabetic retinopathy remains unknown. Methods: We examined whether the quantity per drinking occasion (QPO), including a large QPO, and the combinations of the frequency of alcohol consumption (FAC) and QPO were associated with higher risk of developing severe diabetic retinopathy or diabetic macular edema (DME) using adjusted Cox models. Severe diabetic retinopathy or DME was designated as a vision-threatening treatment-required diabetic eye disease (TRDED). For each man with type 2 diabetes who participated in this longitudinal retrospective cohort study, the date of the earliest health check-up during the inclusion period (April 2008 to August 2016) was set as the start date of follow-up. Results: A TRDED was observed in 425 of 21,392 Japanese men aged 22-74 years with type 2 diabetes during a mean follow-up of 4.3 years (4.6/1000 person-years). Multivariable Cox analysis showed that a large QPO, defined as drinking three drinks or more per occasion, in low- (hazard ratio [HR], 4.76; 95 % CI, 2.06-10.97), intermediate- (HR, 1.58; 95 %CI, 1.001-2.50), and high-frequency categories (HR, 2.01; 95 % CI, 1.20-3.36) was significantly associated with elevated risks of TRDED. Conclusions: In addition to the total amount of ethanol, these findings imply the necessity of avoiding the consumption of large amounts of alcohol on a single occasion to prevent severe diabetic retinopathy or DME.