Short sleep duration may increase impaired fasting glucose risk
MedWire News: People who sleep for less than 6 hours per night have a three-fold increased risk for developing impaired fasting glucose (IFG) compared with those who sleep for 6 to 8 hours per night, a US study suggests.
Lisa Rafalson (State University of New York at Buffalo) and colleagues say that these findings may be related to sleep restriction reducing glucose tolerance and increasing cortisol levels and heart rate variability, as illustrated by previous studies.
They explain: "These neuroendocrine changes interfere with mechanisms that regulate plasma glucose, resulting in a higher steady-state plasma glucose concentration."
The researchers monitored the development of IFG among 363 healthy participants (baseline fasting plasma glucose [FPG] <100 mg/dl),from 1996-2001 to 2003-2004.
Using the Stanford Seven-Day Physical Activity Recall questionnaire, all participants reported their baseline average sleep duration per night as short (<6 hours, n=25), mid-range (6-8 hours, n=314), or long (>8 hours, n=24).
Mid-range sleep was used as the reference "normal" sleep duration.
FPG levels were measured at baseline and at the end of follow-up, with IFG defined as a FPG of less than 100 mg/dl at the baseline examination and between 100 and 125 mg/dl at the follow-up examination.
By the end of the follow-up period, 91 patients had developed IFG, and each of these patients, were matched by age, gender, and year of baseline interview, to three control individuals who did not develop IFG (n=272).
As reported in the Annals of Epidemiology, the risk for IFG was found to be three times greater among short sleepers than mid-range sleepers, after adjustment for diabetes risk factors such as hypertension and a family history of diabetes,.
However, when the effect of insulin resistance was accounted for, the risk for IFG among short sleepers fell to a nonsignificant 2.5-fold increase compared with mid-range sleepers.
This suggests "that insulin resistance explains some but not all of the association," say Rafalson et al.
Of note, no significant association was found between long sleep and IFG development.
The researchers warn that their findings do not conclusively show that sleep restriction is an independent risk factor for IFG development, as "the possibility that short sleep duration may represent a risk marker rather than a causal risk factor for diseases cannot be ruled out at the present time."
They add: "Short sleepers are likely to be characterized by a distinctive pattern of sociodemographic, lifestyle, and comorbid medical conditions that may confound the observed associations."
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By Lauretta Ihonor