Background: Previous studies have suggested that serum ferritin is one of the components of the insulin resistance syndrome in Caucasians. Because serum ferritin levels differ significantly between men and women, variation in the role of ferritin in insulin resistance between the sexes, particularly in Asian populations, is still unknown.
Objective: To examine whether the association between serum ferritin and insulin resistance differs between men and women in randomly selected non-diabetic Chinese subjects.
Design: A retrospective study.
Patients: Four hundred and seventeen non-diabetic Chinese subjects (140 men and 277 women) were studied.
Measurements: Fasting plasma glucose, insulin, lipoproteins and serum ferritin concentrations, as well as plasma glucose and insulin responses to a 75-g oral glucose test (n = 219), were determined.
Results: Fasting serum ferritin concentrations (mean +/- SEM) were significantly higher in men than in women (504 +/- 33 vs. 242 +/- 18 pmol/l, P < 0.001). In women, fasting serum ferritin concentrations correlated significantly with age, body mass index (BMI), amount of body fat, fasting plasma glucose, insulin, cholesterol, triglyceride concentrations, glucose response to an oral glucose load, and homeostasis model assessment (HOMA) of insulin resistance but not with blood pressure, high density lipoprotein (HDL) cholesterol levels and insulin response to oral glucose. On the contrary, none of the above anthropometric and metabolic variables was related to fasting serum ferritin levels in men. HOMA insulin resistance increased progressively across three different tertiles for measured serum ferritin concentrations in women (P < 0.003). In men, HOMA insulin resistance levels were not different among three differing measured serum ferritin levels (P = 0.424). Adjustment for age, BMI and menopause status did not change the significant relationship between HOMA insulin resistance and serum ferritin in women.
Conclusions: We observed that a relationship between serum ferritin levels and insulin resistance exists in women but not in men. This sexual dimorphism merits further investigation.