Normal parathyroid hormone and non‐proliferative diabetic retinopathy in patients with type 2 diabetes

AIMS/INTRODUCTION: To investigate the associations between parathyroid hormone (PTH) and non‐proliferative diabetic retinopathy (NPDR) in patients with type 2 diabetes mellitus. MATERIALS AND METHODS: Data were collected from 2,322 patients with type 2 diabetes mellitus in hospital between 2017 and 2019. The odds ratio (OR) and the corresponding 95% confidence interval related to the quartiles of PTH were obtained by logistic regression analysis after adjusting the potential confounding variation. RESULTS: The patients were stratified into quartiles (Q1–Q4) based on the PTH levels, with the cut‐off limits of ≤23.74, 23.74–29.47, 29.47–37.30 and >37.30 pg/mL in men, and ≤24.47, 24.47–31.22, 31.22–39.49 and >39.49 pg/mL in women. The first quartile (Q1) represents the lowest quartile and the fourth quartile (Q4) is the highest. According to the quartiles (Q1–Q4), the prevalence rate of NPDR in patients showed a significantly decreasing trend (37.9%, 36.3%, 34.0% vs 24.0% in men; 43.2%, 40.5%, 31.1% vs 26.2% in women, both P < 0.05). Independent of age, diabetes duration and other metabolic factors, multivariate logistic regression showed that participants in Q4 had a lower OR of NPDR than those in Q1 (OR 0.443, 95% confidence interval 0.300–0.654, P < 0.001 for men; OR 0.428, 95% confidence interval 0.283–0.646, P < 0.001 for women). CONCLUSIONS: Low serum PTH levels were significantly associated with complications of NPDR in inpatients. Its causality remains to be further studied.