OBJECTIVES: The role of bilirubin is steadily being acknowledged as a biomarker for diabetes complications. The aim of this study is to examine the association between total bilirubin count (TBC) and diabetic retinopathy (DR) in type-2 diabetes (T2DM) patients using national survey data.

METHODS: This cross-sectional study involved data from the 2013-2018 National Health and Nutrition Examination Survey (NHANES). The study sample included patients with HbA1c ≥6.5. Patients having chronic liver disease and pregnancy were excluded. In addition to demographics and TBC (normal range: 0.1-7.1 mg/dl), the following information for the study sample was collected: duration of diabetes (years), systolic and diastolic blood pressure (mmHg), HbA1c (%), TBC (mg/dl) and presence/absence of DR. Descriptive analyses were used to characterize the study sample, and multiple logistic regression was used to identify the risk factors for the development of DR.

RESULTS: The study included an unweighted sample of 1,304 respondents representing 42,314,139 T2DM patients. Overall, there were 318 respondents representing 9,754,290 had DR for a prevalence of 23.05% (95% confidence interval [CI]: 18.99-27.12). The multivariable logistic regression analysis found that TBC, HbA1c (Odds-Ratio [OR]): 1.87, 95% CI: 1.67-2.10), and diabetes duration (OR: 1.14, 95% CI: 1.10-1.17) were significantly associated with DR. The patients with higher TBC had a lower likelihood of developing DR (OR: 0.19, 95% CI: 0.06-0.65).

CONCLUSIONS: The study found an increase in TBC was associated with a reduced risk of DR. Therefore, the TBC can serve as an important biomarker to identify a patient’s risk of developing DR.