Associations of Outdoor Temperature, Bright Sunlight, and Cardiometabolic Traits in Two European Population-Based Cohorts

Personal 24-hour light exposure pattern with obesity and adiposity-related parameters in school-aged children: A cross-sectional study based on compositional data analysis

The 24-h light exposure pattern is an essential feature of circadian rhythms and a potential contributor to body fat health. However, no previous studies have investigated 24-h light exposure patterns in relation to adiposity-related parameters in children. This cross-sectional study recruited school-aged children in Chuzhou, Anhui province, China. Personal 24-h light exposure was collected for 5 days and was divided into four measures: light at daytime (LAD)≥100 lx and <100 lx; light at night (LAN)≥1 lx and <1 lx. Adiposity-related parameters were measured via a body composition analyzer. The association of light exposure with adiposity-related parameters was analyzed using compositional data analysis (CoDA). This study included 831 children 8.53 ± 0.62 years, who were exposed to LAD≥100 lx for 490.1 ± 92.7 min and LAN≥1 lx for 311.2 ± 98.5 min. The proportion of time spent in LAD≥100 lx increasing by 1 % (14.4 min/day) was linked to a decline of 3.10 % in percentage of body fat (PBF). In contrast, prolonged exposure to LAN≥1 lx by 14.4 min/day was associated with an increase of 3.49 % in PBF (All P < 0.01). These associations were robust in boys after gender stratification. CoDA estimated that reducing the time of LAN≥1 lx had more influence in decreasing the odds of childhood overweight/obesity than increasing the time of LAD≥100 lx. Suboptimal 24-h light exposure patterns (brighter nights, darker days) play a threatening role in childhood overweight/obesity. Bright LAN replaced with darker LAN or bright LAD might help decrease the odds of childhood overweight/obesity.

Correlation Studies Between Double-Stranded DNA and Diabetes Mellitus

Background: Diabetes mellitus (DM) is a common chronic endocrine and metabolic disease, and its complications can involve multiple organs and seriously threaten human health. Double-stranded DNA (dsDNA) plays an important role in the autoimmune system; however, the correlation between dsDNA and DM has not been fully studied. Methods: This study recruited 388 diabetic patients and 2970 healthy controls to investigate the relationship between serum dsDNA and DM. The diagnosis of DM was based on the medical diagnostic and treatment standards for DM published by the American Diabetes Association (ADA). The study adhered to ethical principles and obtained informed consent from all participants. We measured serum dsDNA levels in both diabetic patients and healthy controls. The study examined differences in serum dsDNA levels among diabetic patients under various conditions, including different temperatures, ultraviolet (UV) light exposure, seasons, and clinical indicators. Additionally, quantitative PCR was used to assess the expression of dsDNA receptors, single-stranded RNA (ssRNA) receptors, absent in melanoma factor 2 (AIM2)-related inflammatory factors, and Type I interferon (INF) in the peripheral blood of patients and control groups. Results: Peripheral blood serum dsDNA levels were elevated in diabetic patients compared to controls (mean values 1.09 and 0.97 ng/ml, respectively, p < 0.001). We also found that the gene expression levels of dsDNA receptor, ssRNA receptor, AIM2-related inflammatory factors, and Type I IFN in diabetic patients were upregulated. And serum dsDNA levels correlated with clinical indicators. Conclusions: We have confirmed that DM is closely associated with serum dsDNA levels. Therefore, dsDNA detection shows promise as a novel approach for evaluating DM progression, offering new insights for the future diagnosis and treatment of DM.

The mediating role of the TyG index in the relationship between circadian syndrome and cancer among middle-aged and elderly Chinese

BACKGROUND

Circadian Syndrome (CircS) is a significant marker of metabolic imbalance and has been linked to various chronic diseases. However, its relationship with cancer risk remains underexplored. This research aims to explore the relationship between CircS and cancer, while also assessing the possible mediating role of the triglyceride glucose (TyG) index.

METHODS

Baseline data from the 2011 China Health and Retirement Longitudinal Study (CHARLS) and follow-up data from 2015 were analyzed, including participants' sociodemographic characteristics, health behaviors, and metabolic indicators. Linear regression, mediation analysis, and logistic regression were employed to explore relationships between CircS, cancer risk, and the TyG index, with a dose-response analysis conducted on TyG index and cancer risk.

RESULTS

Among 7,864 middle-aged and elderly participants, CircS was significantly and positively associated with cancer risk (r = 0.17, P < 0.001). The TyG index showed a significant correlation with both CircS (r = 0.52, P < 0.001) and cancer (r = 0.15, P < 0.001). Mediation modeling indicated that the TyG index partially mediated the association between CircS and cancer, accounting for 23% of this relationship. Additionally, a significant nonlinear dose-response relationship was observed between the TyG index and cancer risk (Pnonlinear = 0.0024).

CONCLUSION

Circadian syndrome is associated with increased cancer risk, with the TyG index partially mediating this relationship.

Older adults exercising ON TIME: protocol for a randomized controlled cross-over study to assess the effect of physical activity timing on insomnia severity

BACKGROUND

There are increased indications that physical activity timing, irrespective of intensity, impacts insomnia and circadian clock function. Here, we describe the rationale and design of a randomized cross-over study, called ON TIME, to examine the effects of (changing) physical activity timing on insomnia severity and on multiple exploratory outcomes that are linked to circadian clock function.

METHODS

We will conduct a randomized cross-over trial in 40 healthy older adults (aged 65 to 75 years) with subclinical or clinical insomnia (Insomnia Severity Index (ISI) scores of ≥ 10) from the Dutch municipality of Leiden and surroundings. Participants will undergo 3 intervention periods (14 days each) consecutively: one sedentary period and two periods of increased physical activity (one period with morning activity and one period with evening activity). The intervention periods are separated by a wash-out period of 1 week. In both active intervention arms, participants will follow coached or uncoached outdoor physical exercise sessions comprising endurance, strength, and flexibility exercises for 14 days. The primary outcome is change in insomnia severity as measured by the ISI. Additional exploratory outcomes include multiple components of objective sleep quality measured with tri-axial accelerometry and subjective sleep quality assessed by questionnaires as well as dim light melatonin onset and 24-h rhythms in heart rate, heart rate variability, breathing rate, oxygen saturation, mood, and objective emotional arousal and stress. Additionally, we will collect diary data on eating patterns (timing and composition). Finally, fasting blood samples will be collected at baseline and after each intervention period for measurements of biomarkers of metabolic and physiological functioning and expression of genes involved in regulation of the biological clock.

DISCUSSION

We anticipate that this study will make a significant contribution to the limited knowledge on the effect of physical activity timing. Optimizing physical activity timing has the potential to augment the health benefits of increased physical exercise in the aging population.

TRIAL REGISTRATION

Trial was approved by the Medical Ethics Committee Leiden, The Hague, Delft, The Netherlands (June, 2023). The trial was registered in the CCMO-register https://www.toetsingonline.nl/to/ccmo_search.nsf/Searchform?OpenForm under study ID NL82335.058.22 and named ("Ouderen op tijd in beweging" or in English "Older adults exercising on time"). At time of manuscript submission, the trial was additionally registered at ClinicalTrials.gov under study ID: NL82335.058.22 and is awaiting approval.

Inside the Alterations of Circulating Metabolome in Antarctica: The Adaptation to Chronic Hypoxia

Although the human body may dynamically adapt to mild and brief oxygen shortages, there is a growing interest in understanding how the metabolic pathways are modified during sustained exposure to chronic hypoxia. Located at an equivalent altitude of approximately 3,800 m asl, the Concordia Station in Antarctica represents an opportunity to study the course of human adaption to mild hypoxia with reduced impact of potentially disturbing variables else than oxygen deprivation. We recruited seven healthy subjects who spent 10 months in the Concordia Station, and collected plasma samples at sea level before departure, and 90 days, 6 months, and 10 months during hypoxia. Samples were analyzed by untargeted liquid chromatography high resolution mass spectrometry to unravel how the non-polar and polar metabolomes are affected. Statistical analyses were performed by clustering the subjects into four groups according to the duration of hypoxia exposure. The non-polar metabolome revealed a modest decrease in the concentration of all the major lipid classes. By contrast, the polar metabolome showed marked alterations in several metabolic pathways, especially those related to amino acids metabolism, with a particular concern of arginine, glutamine, phenylalanine, tryptophan, and tyrosine. Remarkably, all the changes were evident since the first time point and remained unaffected by hypoxia duration (with the exception of a slight return of the non-polar metabolome after 6 months), highlighting a relative inability of the body to compensate them. Finally, we identified a few metabolic pathways that emerged as the main targets of chronic hypoxia.

Geographic, Gender, and Seasonal Variation of Diabetes: A Nationwide Study With 1.4 Million Participants

CONTEXT

China has experienced a rapid increase in the prevalence of diabetes.

OBJECTIVE

We assessed the prevalence of diabetes among Chinese adults who attended preventive physical examinations and analyzed geographical and gender difference in seasonal variation of fasting blood glucose (FBG).

METHODS

The study used data from 1 390 088 participants attending preventive health examination at 430 health screening centers in 220 cities. Diagnosis of diabetes and prediabetes were based on FBG and glycated hemoglobin A1c and self-reported physician's diagnosis. We calculated age- and sex-standardized prevalence of diabetes according to the sixth Chinese population census data in 2010. Geographical distribution of diabetes and prediabetes were represented on a country map. FBG levels were analyzed to detect seasonal variation adjusted for age and gender by geographic location.

RESULTS

The standardized prevalence of diabetes was 8.70% (95% CI, 8.22%-9.19%), 10.7% in men and 6.61% in women. Among those with diabetes, 43.7% (95% CI, 40.9%-46.5%) were aware of their conditions and 38.5% (95% CI, 36.0%-41.1%) were treated. Only 49.3% (95% CI, 47.0%-51.6%) of treated patients achieved glycemic control. The mean level of FBG was higher in winter than summer and in the northern than the southern region.

CONCLUSION

The prevalence of diabetes was high while the percentages of awareness, treatment, and glycemic control were low among adults. Effective measures are needed to prevent and manage diabetes in China. Geographic and seasonal variation of diabetes should be considered for its prevention and control.

Higher ambient temperature is associated with worsening of HbA1c levels in a Saudi population

BACKGROUND

Ambient temperature is predicted to rise in Saudi Arabia, and how this will impact the health of its population has not been investigated. Saudi Arabia is one of the top ten countries with the highest prevalence of diabetes. The current study investigates the correlation between ambient temperature and HbA1c levels in a group of Saudis in Riyadh.

METHODS

Age, gender, and HbA1c data for six years were obtained from patients' records. The maximum daily temperature of Riyadh city for the same period was obtained.

RESULTS

A total of 168,614 patient records were obtained. There was a statistically significant positive correlation between ambient temperature and HbA1c levels, where for each 1°C increase in average weekly temperature HbA1c increased by 0.007%. Patients were at higher risk of having HbA1c ≥ 7% in high and moderate temperature than in low temperature (P < 0.001, odds ratio (OR): 1.134, and P < 0.001, odds ratio (OR): 1.034; respectively). The mean of HbA1c in females (7.27±1.96) was significantly lower than in males (7.40±1.86), and the probability of males having HbA1c ≥ 7% was about 17.4% higher than females. However, the HbA1c levels in females were significantly more affected by rising temperature compared to males (B = 0.003, P = 0.008).

CONCLUSION

Overall, rise in ambient temperature is associated with worsening HbA1c, which could be harmful to the health of Saudis suffering from diabetes. Possible reasons for the increase in HbA1c could include reduced physical activity, reduced sunlight exposure, and dehydration during hot weather. More research on the relationship between climate change and public health in Saudi Arabia is needed.

Associations between outdoor temperature and bright sunlight with metabolites in two population-based European cohorts

BACKGROUND AND AIMS

Outdoor temperature and bright sunlight may directly and/or indirectly modulate systemic metabolism. We assessed the associations between outdoor temperature and bright sunlight duration with metabolomics.

METHODS AND RESULTS

Cross-sectional analyses were undertaken in non-diabetic individuals from the Oxford BioBank (OBB; N = 6368; mean age 47.0 years, males 44%) and the Netherlands Epidemiology of Obesity (NEO; N = 5916; mean age 55.6 years, males 43%) study. Data on mean outdoor bright sunlight and temperature were collected from local weather stations in the week prior to blood sampling. Fasting serum levels of 148 metabolites, including 14 lipoprotein subclasses, were measured using NMR spectroscopy. Linear regression analyses were performed to assess the associations between mean outdoor temperature and bright sunlight duration with metabolomics adjusted for age, sex, body mass index, season and either outdoor temperature or bright sunlight. A higher mean outdoor temperature was associated with increased serum concentrations of lipoprotein (sub)particles (β (SE) = 0.064 (0.018) SD per 5 °C, p = 5.03e^-4) and certain amino acids such as phenylalanine (0.066 (0.016) SD, p = 6.44e^-05) and leucine (0.111 (0.018) SD, p = 1.25e^-09). In contrast, longer duration of bright sunlight was specifically associated with lower concentrations of very low-density lipoprotein (sub)particles (e.g., VLDL cholesterol (-0.024 (0.005) SD per 1-h bright sunlight, p = 8.06e^-6)). The direction of effects was generally consistent between the OBB and NEO, although effect sizes were generally larger in the OBB.

CONCLUSIONS

Increased bright sunlight duration is associated with an improved metabolic profile whilst higher outdoor temperature may adversely impact cardiometabolic health.

Linking type 2 diabetes mellitus, cardiac hypertrophy and depression in a diurnal animal model

It was recently suggested that the Metabolic Syndrome should be renamed to "Circadian Syndrome". In this context, we explored the effects of living under standard laboratory conditions, where light is the only cycling variable (relevant to human modern life), in a diurnal mammal, on the relationships between affective-like pathology, type 2 diabetes mellitus (T2DM), and cardiac hypertrophy. After 20 weeks, some of the animals spontaneously developed T2DM, depressive and anxiety-like behavior and cardiac hypertrophy. There were significant correlations between levels of anxiety-like behavior and glucose tolerance, and between heart/total body weight ratio and glucose tolerance. Our data suggest a relationship between the development of T2DM, emotional and cardiac pathology as seen in diurnal humans. Furthermore, our data show a possible relationship between reduced daily cycling cues in the laboratory and what has been regularly termed "Metabolic Syndrome" and recently proposed by us to be renamed to "Circadian Syndrome".

The Circadian Syndrome: is the Metabolic Syndrome and much more!

The Metabolic Syndrome is a cluster of cardio-metabolic risk factors and comorbidities conveying high risk of both cardiovascular disease and type 2 diabetes. It is responsible for huge socio-economic costs with its resulting morbidity and mortality in most countries. The underlying aetiology of this clustering has been the subject of much debate. More recently, significant interest has focussed on the involvement of the circadian system, a major regulator of almost every aspect of human health and metabolism. The Circadian Syndrome has now been implicated in several chronic diseases including type 2 diabetes and cardiovascular disease. There is now increasing evidence connecting disturbances in circadian rhythm with not only the key components of the Metabolic Syndrome but also its main comorbidities including sleep disturbances, depression, steatohepatitis and cognitive dysfunction. Based on this, we now propose that circadian disruption may be an important underlying aetiological factor for the Metabolic Syndrome and we suggest that it be renamed the 'Circadian Syndrome'. With the increased recognition of the 'Circadian Syndrome', circadian medicine, through the timing of exercise, light exposure, food consumption, dispensing of medications and sleep, is likely to play a much greater role in the maintenance of both individual and population health in the future.

Associations of Outdoor Temperature, Bright Sunlight, and Cardiometabolic Traits in Two European Population-Based Cohorts

CONTEXT

Seasonal variation in cold and light exposure may influence metabolic health.

OBJECTIVE

We assessed the associations of bright sunlight and outdoor temperature with measures of glucose and lipid metabolism in two populations of middle-aged European subjects.

DESIGN

Cross-sectional study.

SETTING

Two population-based European cohorts.

PARTICIPANTS

Middle-aged nondiabetic subjects from the Oxford Biobank (OBB; N = 4327; mean age, 41.4 years) and the Netherlands Epidemiology of Obesity (NEO) study (N = 5899; mean age, 55.6 years).

INTERVENTIONS

Data on outdoor bright sunlight and temperature collected from local weather stations.

MAIN OUTCOME MEASURES

Insulin resistance and fasting lipid levels. Multivariable regression analyses were adjusted for age, sex, percentage body fat, season, and either outdoor temperature or bright sunlight.

RESULTS

In the OBB cohort, increased bright sunlight exposure was associated with lower fasting insulin [-1.27% (95% CI, -2.09 to -0.47%) per extra hour of bright sunlight], lower homeostatic model assessment for insulin resistance (-1.36%; 95% CI, -2.23 to -0.50), lower homeostatic model assessment for β-cell function (-0.80%; 95% CI, -1.31 to -0.30), and lower triglyceride (-1.28%; 95% CI, -2.07 to -0.50) levels. In the NEO cohort generally unidirectional but weaker associations were observed. No associations between outdoor temperature and measures of glucose or lipid metabolism were detected following adjustment for bright sunlight.

CONCLUSIONS

Bright sunlight, but not outdoor temperature, might be associated with increased insulin sensitivity and lower triglyceride levels.