Serum Retinol and Carotenoids in Association with Biomarkers of Insulin Resistance among Premenopausal Women.

OBJECTIVE: The aim of this study was to investigate how serum retinol and carotenoids ( β -carotene, β -cryptoxanthin, lutein/zeaxanthin, lycopene) are associated with biomarkers of insulin resistance.

RESEARCH METHODS AND PROCEDURES: The BioCycle Study (2005-2007) is a prospective cohort of 259 healthy premenopausal women. Fasting serum samples were collected at up to sixteen clinic visits, from which retinol, carotenoids, insulin, glucose, and sex hormone-binding globulin (SHBG) were measured. Insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). Linear mixed models were used to determine associations adjusting for age, race, body mass index (BMI), education, smoking, physical activity, triglycerides, and energy intake.

RESULTS: Retinol was positively associated with HOMA-IR ( β = 0.19 (95% CI: 0.07, 0.32)) units per ug/mL increase in retinol; the relationship was driven by insulin ( β = 0.20 (95% CI: 0.08, 0.31)). Retinol was inversely associated with SHBG ( β = -0.22 (95% CI: -0.28, -0.16)). Although no significant associations were found between serum carotenoids and HOMA-IR, β -carotene was positively associated with SHBG and β -cryptoxanthin inversely with fasting plasma glucose.

CONCLUSION: Results indicate a possible role for serum retinol in the pathogenesis of type 2 diabetes. However, they do not support a strong association between individual or total serum carotenoids and insulin resistance.