Association between Iron Status and Incident Type 2 Diabetes: A Population-Based Cohort Study

Type 2 diabetes poses a major public health challenge. Here, we conducted a cohort study with a large sample size to determine the association of baseline serum ferritin (SF), a marker of iron status, with incident type 2 diabetes in primary healthcare patients in Catalonia, a western Mediterranean region. A total of 206,115 patients aged 35–75 years without diabetes and with available baseline SF measurements were eligible. The variables analyzed included sociodemographic characteristics, anthropometry, lifestyle, morbidity and iron status (SF, serum iron and hemoglobin). Incident type 2 diabetes during follow-up (2006–2016) was ascertained using the International Classification of Diseases, 10th edition. Cox proportional-hazards models adjusted for multiple baseline confounders/mediators were used to estimate hazard ratios (HRs). Over a median follow-up of 8.4 years, 12,371 new cases of type 2 diabetes were diagnosed, representing an incidence rate of 7.5 cases/1000 persons/year. Since at baseline, the median SF concentration was higher in subjects who developed type 2 diabetes (107.0 µg/L vs. 60.3 µg/L; p < 0.001), SF was considered an independent risk predictor for type 2 diabetes; the multivariable-adjusted HRs for incident type 2 diabetes across SF quartiles 1–4 were 1.00 (reference), 0.95 (95% CI = 0.85–1.06), 1.18 (95% CI = 1.65–1.31) and 1.51 (95% CI = 1.36–1.65), respectively. Our study suggested that higher baseline SF was significantly associated with an increased risk of new-onset type 2 diabetes in Catalan primary healthcare users, supporting the relevance of monitoring iron stores in order to improve the diagnosis and management of diabetes in clinical practice.

Association between serum ferritin and acute coronary heart disease: A population-based cohort study

BACKGROUND AND AIMS

Several studies aiming to determine the association between iron stores and coronary heart disease (CHD) have reported conflicting results. None of them has been performed in a Mediterranean region. Our aim is to assess the association between the level of serum ferritin and the incidence of CHD in a Mediterranean region.

METHODS

We performed a cohort study using a primary health care population database. Primary outcome was incidence of CHD. Subjects aged between 35 and 74 years with serum ferritin (SF) measurements at baseline (January 1, 2006 to December 31, 2008) were included. Cox regression models were used to compute hazard ratios (HRs) and 95%CIs for the associtation between SF and time until CHD outcome.

RESULTS

We include 242,084 subjects with SF levels at baseline. Participants were observed for a median of 8.4 years. During follow-up, 1106 incident cases of CHD were identified. Persons with elevated SF did not have an increased CHD risk at follow-up (adjusted hazard ratio = 0.99; 95%CI 0.94-1.05; p = 0.86 in men, and 0.95; 95%CI 0.81-1.13; p = 0.60 in women).

CONCLUSIONS

Our study, by far the largest, showed that high levels of SF do not confer an increased risk of CHD, and questions its role as a risk factor for this disease.