Interactive effects of serum ferritin and high sensitivity C-reactive protein on diabetes in hypertensive patients.

Background: Hypertensive patients, often characterized by chronic inflammation, are susceptible to diabetes. Evidence suggests that the positive association between serum ferritin (SF) and diabetes was affected by high-sensitivity C-reactive protein (hs-CRP), an inflammation marker. We investigate whether there was an interaction between SF and hs-CRP on diabetes in hypertensive patients.
Methods: We analysed data of 1,735 hypertensive people in this cross-sectional study. Diabetes was diagnosed when fasting blood glucose ≥ 7.0 mmol/L and/or a previous clinical diagnosis of diabetes. Logistic regression models were used to estimate the association of the SF and hs-CRP with diabetes. Multiplicative interaction was evaluated by incorporating a cross-product term for SF and hs-CRP to the logistic regression model. Additive interaction was assessed by calculating the relative excess risk of interaction (RERI) and attributed proportion due to interaction (AP).
Results: In the adjusted analysis, SF (highest vs lowest tertile: odds ratio [OR], 1.61; 95 % confidence interval [CI], 1.20-2.16) was positively associated with diabetes. There was no multiplicative interaction between SF and hs-CRP, but evidence of additive interaction in regard to diabetes (RERI: 0.86; 95 % CI: 0.06-1.67). Compared to the patients with low SF (lower two thirds) and low hs-CRP (≤ 2 mg/L), those with high SF (upper one third) and high hs-CRP (> 2 mg/L) had increased OR for diabetes (adjusted OR: 2.33 [1.65-3.30]), with 37.0 % of the effects attributed to the additive interaction (AP: 0.37; 95 % CI: 0.09-0.65).
Conclusions: Within a cross-sectional study consisting of hypertensive patients, co-exposure to high SF and high hs-CRP was synergistically associated with diabetes. Dietary intervention or pharmacological treatment to lowering SF concentration may help to reduce diabetes morbidity in hypertensive patient with chronic inflammation.
(Copyright © 2021 Elsevier GmbH. All rights reserved.)