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Elevated triglycerides ‘predominant marker’ for disrupted circadian rhythms in older adults
In older adults with overweight or obesity, elevated triglyceride levels are associated with increased circadian rhythm disruption, measured by reductions in both temperature amplitude and stability, according to findings published in the Journal of the Endocrine Society.
“Circadian rhythm disruption and metabolic syndrome are highly associated, but metabolic syndrome encompasses a variety of measurements, and it is still unclear how strongly each factor relates to temperature rhythms,” Brianna D. Harfmann, PhD, of the Barnstable Brown Diabetes and Obesity Center at the University of Kentucky in Lexington, and colleagues wrote. “Therefore, the goal of this study was to begin to identify which variables serve as the strongest predictors of two parameters of circadian rhythms, [temperature amplitude] and [temperature stability].”
Harfmann and colleagues analyzed wrist skin temperature in 34 adults aged 50 to 70 years, with BMI between 27 kg/m² and 40 kg/m², every 10 minutes for 7 consecutive days, as well as metabolic parameters, including BMI, blood pressure, HbA1c, triglycerides, HDL cholesterol and LDL cholesterol. All participants were euthyroid with a normal thyroid-stimulating hormone level, 18 had a history of hypertension, 10 had type 2 diabetes and five were using insulin. Wrist skin temperature was monitored via the iButton device (Thermochron iButton, Embedded Data Systems); temperature amplitude was defined by peak and midline temperature values; temperature stability was defined as the variation in the oscillatory pattern of the individual’s circadian data during data collection.
Within the cohort, participants with metabolic syndrome had lower mean temperature amplitude compared with those without metabolic syndrome (mean, 0.65 vs. 0.98; P = .03), as well as lower mean temperature stability (mean, 79.96 vs. 131.5; P = .04).
In univariate regression analyses, researchers found that triglyceride level, HbA1c and HDL cholesterol, all metabolic syndrome parameters, were correlated with both temperature amplitude and temperature stability, although not independently from one another. However, in multiple linear regression analyses, triglyceride level was the sole parameter independently associated with temperature amplitude and temperature stability (P = .003 and .012, respectively), they wrote.
In stepwise multilinear models that excluded participants without diabetes, researchers found that triglyceride level contributed 68% to the variability of temperature amplitude (r = –0.82; P = .001) and 56% to the variability of temperature stability (r = –0.75; P < .05).
“Therefore, even in the smaller subset of diabetic participants, [triglycerides are] the most prominent factor affecting [temperature amplitude] and [temperature stability],” the researchers wrote. “Overall, these data suggest that [triglyceride level] has the greatest impact on circadian temperature rhythms and is the predominant [metabolic syndrome] marker for disrupted circadian rhythms.” – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.