Toenails give clues about diabetes risk
MedWire News: Measuring concentrations of selenium in the toenail may help physicians determine risk for the onset of Type 2 diabetes, suggest US researchers.
Higher levels of toenail selenium were associated with lower incidence of diabetes in a prospective study of initially healthy individuals, they report.
Selenium is involved in antioxidant defense systems which actively protect against damage from free radicals and reactive oxygen species, explain Kyong Park (Yeungnam University, Gyeongsang, South Korea) and team in Diabetes Care.
"Increased free radical levels impair glucose-stimulated insulin secretion, decrease gene expression of key β-cell genes, and induce cell death."
Despite compelling biologic evidence suggesting that selenium may reduce incident diabetes, results from prior cross-sectional studies have been conflicting, note the researchers, who say that to their knowledge, no prior investigations have followed large numbers of individuals with both biomarker measures and sufficiently long durations of follow-up.
The team therefore prospectively evaluated whether selenium intake was associated with onset of diabetes, using baseline and follow-up data for 3630 women from the Nurses' Health Study (NHS) and 3535 men from the Health Professionals Follow-up Study (HPFS).
The participants provided toenail clippings at study baseline (1982-1983 in NHS, 1986-1987 in HPFS) and toenail selenium concentrations were obtained using neutron activation analysis. The participants were then followed up biennially through 2008 by questionnaire for incidence of diabetes.
"Toenail Se [selenium] concentrations are valid biomarkers of Se consumption, responding to long-term changes in dietary consumption and correlating with whole blood and serum Se levels," explain Park and colleagues.
The researchers report that during 142,550 person-years of follow-up, there were 780 cases of incident diabetes.
The mean concentration of toenail selenium was 0.84 µg/g in men and 0.77 µg/g in women.
The study revealed that toenail selenium concentrations were inversely associated with incidence of Type 2 diabetes after adjustment for age, gender, geographic region, smoking status, alcohol intake, physical activity, body mass index, selenium supplement use, multivitamin use, and dietary risk factors.
The pooled relative risk for diabetes onset across increasing quintiles of selenium, compared with the lowest quintile, were 0.91, 0.78, 0.72, and 0.76, respectively, in both cohorts combined.
Further analysis suggested monotonic dose-response relationships between selenium and diabetes onset, report the authors.
"Our results support the need for further investigations into the effects of selenium at both dietary and higher doses, on metabolic pathways and risk factors for Type 2 diabetes," they conclude.
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By Sally Robertson