Women with an insufficient or deficient level of serum 25-hydroxyvitamin D are more likely to have a fasting blood glucose level of at least 100 mg/dL, indicating greater risk for type 2 diabetes, according to findings published in Menopause.
“Altered blood glucose is a major risk factor for morbidities like diabetes mellitus and cardiovascular disease,” Tânia Valladares, MD, MSc, a gynecologist and obstetrician with the department of mother and child health at the University of Sao Paulo School of Public Health, Brazil, told Endocrine Today. “If there is a relationship between glucose and vitamin D, and hypovitaminosis D is a consequence of lifestyle on general health (poor sun exposure, malnutrition, etc), this knowledge could lead to feasible means of reducing the damage resulting from that relationship.”
In a cross-sectional study, Valladares and colleagues analyzed data from 680 women enrolled in the Pindamonhangaba Family Health Program in Brazil. Women provided fasting blood samples, underwent physical exams and completed questionnaires on medical history. Researchers performed bivariate analyses to determine whether a blood glucose level of at least 100 mg/dL was associated with a 25-(OH)D level of less than 20 ng/mL or less than 30 ng/mL.
Within the cohort, mean fasting glucose was 105 mg/dL and 176 women (25.8%) reported having diabetes, with 52.2% of those women using at least one antidiabetes medication and 17% using insulin. Mean 25-(OH)D level for the cohort was 26.4 ng/mL. Researchers found that 26.6% of women had a 25-(OH)D level of less than 20 ng/mL, and 65.4% of women had a 25-(OH)D level of less than 30 ng/mL. There were no associations observed between vitamin D level and age or skin color.
“Even in sunny regions of the Earth, like Brazil, the prevalence of low serum concentrations of vitamin D is high,” Valladares said.
Researchers found that a blood glucose level of at least 100 mg/dL was positively associated with BMI, age, hypertension status and a serum 25-(OH)D level of less than 20 ng/mL or less than 30 ng/mL. A blood glucose level of at least 100 mg/dL was not associated with vitamin D supplementation (OR = 0.89; 95% CI, 0.53-1.51) or self-reported habitual exposure to the sun (OR = 1.03; 95% CI, 0.85-1.25). Results persisted in Poisson models adjusted for BMI, age and systolic blood pressure.
“Because of the study design, it is not possible to prove a direct effect of vitamin D on glucose levels,” Valladares said. “Other factors can possibly influence both vitamin D and glucose, like a sedentary lifestyle and lack of outdoor activities. Thus, intervention studies are needed to clarify the relationship between vitamin D and glucose.” – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.