Dietary Inflammatory Index and diabetic retinopathy risk in US adults: findings from NHANES (2005-2008)

Background Inflammation is associated with the pathophysiology of diabetic retinopathy (DR). Within the framework of complete dietary patterns, the Dietary Inflammatory Index (DII) was formulated to evaluate the inflammatory properties inherent in a diet. The main purpose of the current study was to assess the relationship between DII and DR using National Health and Nutrition Examination Survey (NHANES). Methods The original sample size included 1,148 diabetes patients out of 2005-2008 NHANES surveys. Twenty-four-hour dietary consumptions were used to calculate the DII scores. Demographic characteristics and retina examinations were collected for the comparison between DR and non-DR groups in diabetes patients. The relationship between DII and DR was analyzed by a logistic regression model. Results 227 subjects (110 non-DR and 117 DR) were selected in the analyses by using undersampling method to balance the sample size. Compared with non-DR group, DR group had higher DII values (1.14 +/- 0.29 vs. 1.49 +/- 0.21, p = 0.32), higher levels of HbA1c (6.8 +/- 1.1% vs. 7.7 +/- 2.6%, p < 0.001), longer duration of diabetes (6.52 +/- 12 years vs. 14 +/- 11 years, p < 0.001). The odds rate (OR) of DII for DR from the logistic regression was 1.38 (95%CI 1.06-1.81, p < 0.001). HbA1c, diabetes duration and obesity were important influencing factors, and their ORs were 1.81 (95% CI:1.31-2.50), 1.12 (95%CI:1.04-1.20), 4.01 (95%CI:1.12-14.32), respectively. In addition, the most important dietary indices for DR were different across males and females. Conclusions The current study demonstrates that a higher DII is associated with an increased risk of DR in US adults. Considering diet as a modifiable factor, limiting pro-inflammatory diets or encouraging an anti-inflammatory diet may be a promising and cost-effective method in the management of DR.