Physical Activity, Blood Glucose and C-Peptide in Healthy School-Children, a Longitudinal Study

Exercise improves body composition, physical fitness, and blood levels of C-peptide and IGF-1 in 11- to 12-year-old boys with obesity

Introduction

Exercise is vital in preventing and treating obesity. Despite its importance, the understanding of how exercise influences childhood obesity at the biochemical level is limited. In this study, we explore the effects of a 16-week exercise program (EP) on body composition, physical fitness, and the blood levels of hormones related to obesity.

Methods

Sixteen boys with obesity (n = 16) and seventeen boys without obesity (n = 17) took part in an EP comprising sports games and aerobic and resistance exercises. We examined alterations in body composition and physical fitness. In addition, we measured circulating hormone levels, including C-peptide, resistin, insulin-like growth factor 1 (IGF-1), and growth hormone (GH), in the blood.

Results

Body fat percentage (BFP) decreased from 37.61% at pre-EP to 29.16% at post-EP in the obese group, but not in the non-obese group. The EP decreased C-peptide (4.58 ng/mL vs. 2.96 ng/mL, p < 0.001) and resistin levels (14.05 ng/mL vs. 11.06 ng/mL, p < 0.001) in the obese group. After the EP, significant improvement in IGF-1 (non-obese: 265.56 ng/mL vs. 311.81 ng/mL, p < 0.001; obese: 224.74 ng/mL vs. 272.89 ng/mL, p < 0.001) and GH levels (non-obese: 3.91 ng/mL vs. 4.80 ng/mL, p < 0.05; obese: 1.76 ng/mL vs. 2.51 ng/mL, p < 0.05) were observed in both groups. Lower C-peptide levels were associated with BFP (r = 0.447, p = 0.009) and muscle mass (r = -0.385, p = 0.02), whereas enhanced IGF-1 levels correlated with increased muscle strength (r = 0.343, p = 0.05) and cardiovascular fitness (r = 0.347, p = 0.04). Multiple linear regression analysis revealed that cardiovascular fitness variability and BFP in the obese group were determined by C-peptide (β = -0.054, p < 0.001) and IGF-1 levels (β = -2.936, p < 0.05), respectively.

Discussion

Exercise may induce positive effects on improvements in body composition and physical fitness, as well as on blood levels of metabolic biochemicals such as C-peptide and IGF-1, in adolescent boys with obesity.

Physical activity modified association of urinary metals mixture and fasting blood glucose in children: From two panel studies

There is unclear evidence available on the associations between multiple metals and fasting blood glucose (FBG) in children, and whether they could be beneficial from physical activity. We included 283 children aged 4-12 years from two panel studies with 4-consecutive morning urinary 13 essential metals and 10 non-essential metals repeated across 3 seasons. We employed multiple informant model, linear mixed-effect model, and quantile g-computation to evaluate associations of single metal and their mixture with FBG and interactions with extra-school activity. The results showed that positive relations of multiple essential metals (aluminum, chromium, copper, iron, molybdenum (Mo), nickel, selenium (Se), strontium, zinc) and non-essential metals (arsenic (As), cadmium (Cd), rubidium, titanium (Ti), thallium) with FBG were the strongest at lag 0 (the health examination day), especially in overweight & obesity children (FDR <0.05). The strongest effect presented 1-fold increment in As was related to FBG increased 1.66% (95%CI: 0.84%, 2.48%) in overweight & obesity children. Notably, modification of extra-school activity showed significant, and the effects of multiple metals on FBG were attenuated in children taking total extra-school activity ≥1 h/day, and only one type of which, low or moderate & high intensity extra-school activity reached 20 min/day (Pint <0.05). For instance, each 1-fold increased As was associated with 1.41% increased FBG in overall children taking total extra-school activity <1 h/day, while that of 0.13% in those ≥1 h/day. Meanwhile, mixture of all, essential and non-essential metals were associated with increased FBG, a trend that decreased and became nonsignificant in children having certain extra-school activity, which were dominated by Mo, Se, Ti, Cd. And such relations were substantially beneficial from extra-school activity in overweight & obesity children. Accordingly, multiple essential and non-essential metals, both individual and in mixture, were positively related to FBG in children, which might be attenuated by regular physical activity.

Effects of accelerometry-derived physical activity energy expenditure on urinary C-peptide levels in a wild primate (Papio ursinus)

Animals have finite energy reserves for growth, survival, and reproduction and must maintain a stable energy balance. Measuring energy balance in the wild, however, is beset with methodological challenges. Quantification of urinary C-peptide (uCP), a proxy for insulin secretion, has enabled researchers to non-invasively estimate energy balance, and positive relationships between uCP levels and energy intake have been documented in numerous non-human primates. Comparatively few studies show that, consistent with insulin physiology, energy expenditure also alters levels of uCP. The timescale and extent of this relationship, however, remains unclear given the reliance on crude measures of activity and inferred energy expenditure. Here, for the first time, we test for effects of accelerometer-derived Vectorial Dynamic Body Acceleration (VeDBA) - a continuous measure of physical activity energy expenditure - on urinary C-peptide (uCP) levels in n = 12 wild chacma baboons (Papio ursinus). Applying a model selection approach, we show that VeDBA summed over short timescales (30 min to 1 h) prior to urine collection was negatively associated with uCP levels. Using the acceleration-based time individuals spent 'non-stationary' (i.e. locomoting) prior to urine collection as a predictor - instead of summed VeDBA - revealed similar but less clear results. Overall, the negative relationship between VeDBA and uCP levels highlights the importance of quantifying physical activity energy expenditure when using uCP measures to estimate energy balance and has potential implications for the field of energetics accelerometry.

Beta cell function in participants with single or multiple islet autoantibodies at baseline in the TEDDY Family Prevention Study: TEFA

Aim

The aim of the present study was to assess beta cell function based on an oral glucose tolerance test (OGTT) in participants with single islet autoantibody or an intravenous glucose tolerance test (IvGTT) in participants with multiple islet autoantibodies.

Materials and methods

Healthy participants in Sweden and Finland, between 2 and 49.99 years of age previously identified as positive for a single (n = 30) autoantibody to either insulin, glutamic acid decarboxylase, islet antigen-2, zinc transporter 8 or islet cell antibodies or multiple autoantibodies (n = 46), were included. Participants positive for a single autoantibody underwent a 6-point OGTT while participants positive for multiple autoantibodies underwent an IvGTT. Glucose, insulin and C-peptide were measured from OGTT and IvGTT samples.

Results

All participants positive for a single autoantibody had a normal glucose tolerance test with 120 minutes glucose below 7.70 mmol/L and HbA1c values within the normal range (<42 mmol/mol). Insulin responses to the glucose challenge on OGTT ranged between 13.0 and 143 mIU/L after 120 minutes with C-peptide values between 0.74 and 4.60 nmol/L. In Swedish participants, the first-phase insulin response (FPIR) on IvGTT was lower in those positive for three or more autoantibodies (n = 13; median 83.0 mIU/L; range 20.0-343) compared to those with two autoantibodies (n = 15; median 146 mIU/L; range 19.0-545; P = .0330).

Conclusion

Participants positive for a single autoantibody appeared to have a normal beta cell function. Participants positive for three or more autoantibodies had a lower FPIR as compared to participants with two autoantibodies, supporting the view that their beta cell function had deteriorated.

Regular physical activity as a physiological factor contributing to extend partial remission time in children with new onset diabetes mellitus-Two years observation

BACKGROUND

Beneficial effects of physical activity (PA) are confirmed in patients with all types of long-lasting diabetes. The possibility of PA to be a factor prolonging remission phase in children with new-onset type 1 diabetes (T1D) has not yet been thoroughly studied.

OBJECTIVE

The aim of the study was to elucidate the influence of regular PA on prevalence of partial remission (PR), metabolic control, daily insulin requirement (DIR), and C-peptide secretion in children newly diagnosed with T1D.

METHODS

A total of 125 children diagnosed with T1D were studied prospectively for 2 years. Patients were controlled every 3 months and advised with PA according to ISPAD recommendations. Anthropometric parameters, HbA1c, C-peptide level and DIR were analyzed. Patients' PA level was assessed using a self-designed questionnaire.

RESULTS

We classified 43% of participants as physically-active. In this group, lower HbA1c after 2 years, lower DIR after 3, 6 months, and after 2 years (all P < .05) were found. At discharge from hospital, the prevalence of DIR < 0.5 U/kg/24 h with near normoglycemia was similar in both groups. Then, we observed higher PR prevalence in active group lasting over time and resulting in 44% vs 13% after 2 years (P < .001). C-peptide after 2 years was comparable in both groups, with higher prevalence of clinically significant levels (>0.2 nmoL/L) in active group: 79.6% vs 61.4% (P = .029).

CONCLUSIONS

These data support the view that regular PA may essentially contribute to extending PR time in pediatric diabetes, and may therefore lead to a better long-term metabolic control of the disease.

Impaired fasting glucose prevalence surge among Iranian adolescents in a decade: The Tehran Lipid and Glucose Study

PURPOSE

Impaired fasting glucose (IFG) is associated with incident diabetes, cardiovascular risk, and markers of atherosclerosis in early adulthood. We aimed to explore the 10-year change in IFG prevalence among adolescent participants of the Tehran Lipid and Glucose Study, a population-based study from Iran.

METHODS

For our study, we used data on fasting plasma glucose (FPG), anthropometric, and demographic information of 11 to 19-year-old adolescents in study periods I (1999-2005; 1415 boys, 1583 girls) and II (2011-2014; 477 boys, 469 girls). Sex-adjusted and sex-stratified multivariable logistic regression models were used to assess the relationship of the study period (reference: study period I) with IFG.

RESULTS

The prevalence of IFG, general obesity, and central obesity increased from 7%, 13.3%, and 18.8% in study period I to 16.6%, 24%, and 37.4% in study period II; while a favorable trend was seen for blood pressure, triglycerides, and high-density lipoprotein cholesterol. In the fully adjusted model, being older (age group 15-19 vs 11-14 years) and female sex were associated with lower risk. Being overweight and obese increased the risk by risk ratios (confidence interval) of 1.57 (1.17-2.11) and 1.63 (1.15-2.30), respectively. Central adiposity did not remain as an independent risk factor. Nevertheless, study period persisted as a significant factor despite all adjustments [2.20 (1.81-2.68)]. Results in the sex-stratified models were generally the same.

CONCLUSION

Our results demonstrated that the over 2-fold rise in IFG prevalence among adolescents was not solely dependent on general and central obesity.

Sugar in mind: Untangling a sweet and sour relationship beyond type 2 diabetes

It is widely recognised that type 2 diabetes (T2D) represents a major disease burden but it is only recently that its role in neurodegeneration has attracted more attention. This research has shown that T2D is associated with impaired cerebral health, cognitive decline and dementia. However, the impact on the brain of progressive metabolic changes associated with the pre-clinical development of the disease is less clear. The aim of this review is to comprehensively summarise how the emergence of risk factors and co-morbid conditions linked to the development of T2D impact cerebral health. Particular attention is directed at characterising how normal but elevated blood glucose levels in individuals without T2D contribute to neurodegenerative processes, and how the main risk factors for T2D including obesity, physical activity and diet modulate these effects. Where available, evidence from the animal and human literature is contrasted, and sex differences in risk and outcomes are highlighted.

Comparisons of pedometer-determined weekday physical activity among Swedish school children and adolescents in 2000 and 2017 showed the highest reductions in adolescents

AIM

This study compared differences in weekday physical activity among school children and adolescents in middle-class communities in south-eastern Sweden in 2000 and 2017.

METHODS

Data were drawn from two independent cross-sectional cohorts of children and adolescents aged 8, 11 and 14. The same six schools, protocols, procedures and instruments were used in both years, with 332 subjects in 2000 and 562 in 2017. Mean steps per day (SPD) were measured with a Yamax SW-200 pedometer.

RESULTS

The mean weekday SPD was similar among eight-year-old girls in both years, but 8% (p = 0.040) higher among eight-year-old boys in 2017. However, among 11-year-old children, the mean SPD were 12% lower among both girls (p = 0.033) and boys (p = 0.001). The SPD among 14-year-old adolescents were 24% (p = 0.012) and 30% (p < 0.001) lower among girls and boys, respectively.

CONCLUSION

This school-based study from south-eastern Sweden showed that weekday physical activity differed between age groups in 2000 and 2017. The highest reductions were seen among older children and adolescents, particularly 14-year-old girls and boys. The only group that increased was eight-year-old boys, with no significant change in eight-year-old girls. A possible explanation might be the dramatically increased use of the Internet on phones and tablets.

Physical activity is associated with lower insulin and C-peptide during glucose challenge in children and adolescents with family background of diabetes

AIMS

Children and adolescents with a family history of diabetes are at increased risk of overweight, but little is known about the potentially beneficial effects of physical activity on these children. The objective of this study was to investigate the association between moderate to vigorous physical activity (MVPA) and metabolic and inflammatory risks in children and adolescents with a family background of Type 1 diabetes or gestational diabetes.

METHODS

Valid MVPA measurements, made with accelerometers, were available from 234 participants (median age, 10.2 years) who had a first-degree relative with either Type 1 or gestational diabetes. Anthropometric and metabolic measurements were made and cytokines measured, and were correlated with MVPA measurements, with stepwise adjustment for confounding factors, in a cross-sectional analysis.

RESULTS

MVPA was negatively associated with insulin and C-peptide during challenge with an oral glucose tolerance test. MVPA was also significantly positively associated with the insulin sensitivity index, whereas no consistently significant associations were found between MVPA and BMI, blood pressure or cytokine levels.

DISCUSSION

Our findings indicate that physical activity may have beneficial effects on insulin and C-peptide metabolism in children and adolescents with a family background of diabetes, but show no evidence of a protective association with other health-related outcomes.

Physical activity in adolescents and children and relationship to metabolic health

PURPOSE OF REVIEW

To summarize the recent developments relating to the role of physical activity in improving insulin resistance and metabolic syndrome in children and adolescents.

RECENT FINDINGS

The current literature strengthens previous findings on the relationship between physical activity and metabolic health in children; suggests a protective role for physical activity in the setting of obesity; examines population-specific findings; addresses specific effects of different modalities of physical activity in improving health; reveals potential mediators in the relationship between physical activity and metabolic health; and suggests new markers of metabolic health that could potentially be used as outcomes in future physical activity studies.

SUMMARY

Recent research generally confirms the role of physical activity in decreasing insulin resistance and metabolic syndrome in children and adolescents. However, the current literature is limited by unstandardized research methods and definitions, and also aggregation of different age groups, genders, and weight status. Future research should address these issues to offer targeted physical activity interventions.

Use of green spaces and blood glucose in children; a population-based CASPIAN-V study

A limited but emerging body of evidence is suggestive for a beneficial association between contact with green spaces and glucose homeostasis in adults; however, such an evidence for children is scarce. We evaluated the association between time spent in green spaces and fasting blood glucose (FBG) levels and impaired fasting glucose (IFG, FBG≥110 mg/dL) in a population-based multicentric sample of 3844 Iranian schoolchildren aged 7-18 years (2015). Participants were instructed to report the average hours per week spent in green spaces separately during each season and in each type of green space (parks, woods/other natural green spaces, and private gardens/agricultural field) for a 12-month period preceding the interview. We developed linear and logistic mixed effects models with centre as random effect to evaluate the association of time spent in green spaces (separately for each type as well as all types together) with FBG and IFG, respectively, controlled for a wide range of covariates including household indicators of socioeconomic status. We observed inverse associations between time spent in green spaces, especially in natural green spaces, and FBG levels. Specifically, 1.83 h increase in the total time spent in green spaces was associated with -0.5 mg/dl (95% confidence intervals: -0.9, -0.1) change in FBG levels. We also observed reduced risk of IFG associated with time spent in green spaces; however, the association was statistically significant only for the time spent in natural green spaces. There were suggestions for stronger associations for those residing in urban areas and those from lower socioeconomic status groups; however, the interaction terms for socioeconomic status and urbanity were not statistically significant. Further longitudinal studies are required to replicate our findings in other settings with different climates and population susceptibilities.