Seasonality of Insulin Resistance, Glucose, and Insulin among Middle-Aged and Elderly Population: The Rotterdam Study.

Seasonality of Insulin Resistance, Glucose, and Insulin among Middle-Aged and Elderly Population: The Rotterdam Study.

J Clin Endocrinol Metab. 2017 Dec 28;:

Authors: Cepeda M, Muka T, Ikram MA, Franco OH, Schoufour JD

Abstract
Context: There are discrepancies in the seasonality of insulin resistance (IR) across the literature, probably due to age-related differences in the seasonality of lifestyle factors and thermoregulation mechanisms.
Objective: To estimate the seasonality of IR according to the homeostatic model assessment-insulin resistance (HOMA-IR), glucose, and insulin levels; and to examine the role of lifestyle markers (body mass index (BMI) and physical activity) and meteorological factors, according to age.
Design, setting and participants: Seasonality was examined using cosinor analysis among middle-aged (45-65 years) and elderly (≥65 years) participants of a population-based Dutch cohort. We analyzed 13,622 observations from 8,979 participants (57.6% women) without diagnosis of diabetes and fasting glucose <7mmol/L. BMI was measured, physical activity was evaluated using a validated questionnaire, and meteorological factors (daily mean ambient temperature, mean relative humidity, total sunlight hours, and total precipitation) were obtained from local records. Seasonality estimates were adjusted for confounders.
Results: Among the middle-aged, seasonal variation estimates were: 0.12units (95%CI 0.03, 0.20) for HOMA-IR, 0.32µIU/mL (-0.05, 0.69) for insulin, and 0.05mmol/L (0.01, 0.09) for glucose. These had a summer peak and lifestyle markers explained the pattern. Among the elderly, seasonal variations were: 0.29units (0.21, 0.37) for HOMA-IR, 0.93µIU/mL (0.58, 1.28) for insulin, and 0.02mmol/L (-0.01, 0.05) for glucose. These had a winter peak and ambient temperature explained the pattern.
Conclusion: Impaired thermoregulation mechanisms could explain the winter peak of IR among elderly people without diabetes. The seasonality of lifestyle factors may explain the seasonality of glucose.

PMID: 29301043 [PubMed - as supplied by publisher]

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