Janine Malcolm

Effects of Performing Resistance Exercise Before Versus After Aerobic Exercise on Glycemia in Type 1 Diabetes

OBJECTIVE To determine the effects of exercise order on acute glycemic responses in individuals with type 1 diabetes performing both aerobic and resistance exercise in the same session. RESEARCH DESIGN AND METHODS Twelve physically active individuals with type 1 diabetes (HbA1c 7.1 ± 1.0%) performed aerobic exercise (45 min of running at 60% V̇o2peak) before 45 min of resistance training (three sets of eight, seven different exercises) (AR) or performed the resistance exercise before aerobic exercise (RA). Plasma glucose was measured during exercise and for 60 min after exercise. Interstitial glucose was measured by continuous glucose monitoring 24 h before, during, and 24 h after exercise. RESULTS Significant declines in blood glucose levels were seen in AR but not in RA throughout the first exercise modality, resulting in higher glucose levels in RA (AR = 5.5 ± 0.7, RA = 9.2 ± 1.2 mmol/L, P = 0.006 after 45 min of exercise). Glucose subsequently decreased in RA and increased in AR over the course of the second 45-min exercise bout, resulting in levels that were not significantly different by the end of exercise (AR = 7.5 ± 0.8, RA = 6.9 ± 1.0 mmol/L, P = 0.436). Although there were no differences in frequency of postexercise hypoglycemia, the duration (105 vs. 48 min) and severity (area under the curve 112 vs. 59 units ⋅ min) of hypoglycemia were nonsignificantly greater after AR compared with RA. CONCLUSIONS Performing resistance exercise before aerobic exercise improves glycemic stability throughout exercise and reduces the duration and severity of postexercise hypoglycemia for individuals with type 1 diabetes.

Resistance Versus Aerobic Exercise: Acute effects on glycemia in type 1 diabetes

OBJECTIVE In type 1 diabetes, small studies have found that resistance exercise (weight lifting) reduces HbA1c. In the current study, we examined the acute impacts of resistance exercise on glycemia during exercise and in the subsequent 24 h compared with aerobic exercise and no exercise. RESEARCH DESIGN AND METHODS Twelve physically active individuals with type 1 diabetes (HbA1c 7.1 ± 1.0%) performed 45 min of resistance exercise (three sets of seven exercises at eight repetitions maximum), 45 min of aerobic exercise (running at 60% of Vo2max), or no exercise on separate days. Plasma glucose was measured during and for 60 min after exercise. Interstitial glucose was measured by continuous glucose monitoring 24 h before, during, and 24 h after exercise. RESULTS Treatment-by-time interactions (P < 0.001) were found for changes in plasma glucose during and after exercise. Plasma glucose decreased from 8.4 ± 2.7 to 6.8 ± 2.3 mmol/L (P = 0.008) during resistance exercise and from 9.2 ± 3.4 to 5.8 ± 2.0 mmol/L (P = 0.001) during aerobic exercise. No significant changes were seen during the no-exercise control session. During recovery, glucose levels did not change significantly after resistance exercise but increased by 2.2 ± 0.6 mmol/L (P = 0.023) after aerobic exercise. Mean interstitial glucose from 4.5 to 6.0 h postexercise was significantly lower after resistance exercise versus aerobic exercise. CONCLUSIONS Resistance exercise causes less initial decline in blood glucose during the activity but is associated with more prolonged reductions in postexercise glycemia than aerobic exercise. This might account for HbA1c reductions found in studies of resistance exercise but not aerobic exercise in type 1 diabetes.

Glucose tolerance of offspring of mother with gestational diabetes mellitus in a low‐risk population

Aims  To describe the prevalence of impaired glucose tolerance and obesity in offspring of mothers whose pregnancies were complicated by gestational diabetes mellitus (GDM) in a low‐risk population and to investigate the effect on these outcomes of minimal intervention compared with tight control for management of GDM.

Effects of Aerobic Training, Resistance Training, or Both on Percentage Body Fat and Cardiometabolic Risk Markers in Obese Adolescents: The Healthy Eating Aerobic and Resistance Training in Youth Randomized Clinical Trial

IMPORTANCE Little evidence exists on which exercise modality is optimal for obese adolescents. OBJECTIVE To determine the effects of aerobic training, resistance training, and combined training on percentage body fat in overweight and obese adolescents. DESIGN, SETTING, AND PARTICIPANTS Randomized, parallel-group clinical trial at community-based exercise facilities in Ottawa (Ontario) and Gatineau (Quebec), Canada, among previously inactive postpubertal adolescents aged 14 to 18 years (Tanner stage IV or V) with body mass index at or above the 95th percentile for age and sex or at or above the 85th percentile plus an additional diabetes mellitus or cardiovascular risk factor. INTERVENTIONS After a 4-week run-in period, 304 participants were randomized to the following 4 groups for 22 weeks: aerobic training (n = 75), resistance training (n = 78), combined aerobic and resistance training (n = 75), or nonexercising control (n = 76). All participants received dietary counseling, with a daily energy deficit of 250 kcal. MAIN OUTCOMES AND MEASURES The primary outcome was percentage body fat measured by magnetic resonance imaging at baseline and 6 months. We hypothesized that aerobic training and resistance training would each yield greater decreases than the control and that combined training would cause greater decreases than aerobic or resistance training alone. RESULTS Decreases in percentage body fat were -0.3 (95% CI, -0.9 to 0.3) in the control group, -1.1 (95% CI, -1.7 to -0.5) in the aerobic training group (P = .06 vs controls), and -1.6 (95% CI, -2.2 to -1.0) in the resistance training group (P = .002 vs controls). The -1.4 (95% CI, -2.0 to -0.8) decrease in the combined training group did not differ significantly from that in the aerobic or resistance training group. Waist circumference changes were -0.2 (95% CI, -1.7 to 1.2) cm in the control group, -3.0 (95% CI, -4.4 to -1.6) cm in the aerobic group (P = .006 vs controls), -2.2 (95% CI -3.7 to -0.8) cm in the resistance training group (P = .048 vs controls), and -4.1 (95% CI, -5.5 to -2.7) cm in the combined training group. In per-protocol analyses (≥ 70% adherence), the combined training group had greater changes in percentage body fat (-2.4, 95% CI, -3.2 to -1.6) vs the aerobic group (-1.2; 95% CI, -2.0 to -0.5; P = .04 vs the combined group) but not the resistance group (-1.6; 95% CI, -2.5 to -0.8). CONCLUSIONS AND RELEVANCE Aerobic, resistance, and combined training reduced total body fat and waist circumference in obese adolescents. In more adherent participants, combined training may cause greater decreases than aerobic or resistance training alone. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00195858.

Through the looking glass: gestational diabetes as a predictor of maternal and offspring long-term health.

Gestational diabetes mellitus (GDM) is gaining in importance as a predictor of future health risks for women and their offspring. In women, it is associated with increased long‐term risks of diabetes, metabolic syndrome and increased cardiovascular disorders. For offspring of mothers with GDM, risks of GDM include abnormal glucose tolerance, obesity and metabolic syndrome. This review presents the evidence for GDM as a predictor of long‐term health risks for mothers and their offspring. We highlight GDM as an opportune time to screen for and possibly intervene to prevent adverse health outcomes for both women and their offspring. Copyright

Video Game Playing Is Independently Associated with Blood Pressure and Lipids in Overweight and Obese Adolescents

Objective To examine the association between duration and type of screen time (TV, video games, computer time) and blood pressure (BP) and lipids in overweight and obese adolescents. Design This is a cross-sectional study of 282 overweight or obese adolescents aged 14–18 years (86 males, 196 females) assessed at baseline prior to beginning a lifestyle intervention study for weight control. Sedentary behaviours, defined as hours per day spent watching TV, playing video games, recreational computer use and total screen time were measured by self-report. We examined the associations between sedentary behaviours and BP and lipids using multiple linear regression. Results Seated video gaming was the only sedentary behaviour associated with elevated BP and lipids before and after adjustment for age, sex, pubertal stage, parental education, body mass index (BMI), caloric intake, percent intake in dietary fat, physical activity (PA) duration, and PA intensity. Specifically, video gaming remained positively associated with systolic BP (adjusted r = 0.13, β = 1.1, p<0.05) and total cholesterol/HDL ratio (adjusted r = 0.12, β = 0.14, p<0.05). Conclusions Playing video games was the only form of sedentary behaviour that was independently associated with increased BP and lipids. Our findings provide support for reducing time spent playing seated video games as a possible means to promote health and prevent the incidence of cardiovascular disease (CVD) risk factors in this high risk group of overweight and obese adolescents. Future research is needed to first replicate these findings and subsequently aim to elucidate the mechanisms linking seated video gaming and elevated BP and lipids in this high risk population. Trial Registration Clinicaltrials.gov NCT00195858

Prevalence of metabolic markers of insulin resistance in offspring of gestational diabetes pregnancies

In utero hyperglycemia has been associated with insulin resistance (IR) in children; however, there are limited data in low‐risk populations. The purpose of this study was to describe the prevalence of metabolic markers of IR in a primarily Caucasian cohort of gestational diabetes mellitus (GDM) offspring aged 7–11 yr (mean 9.1) and to correlate offspring with maternal indexes. Sixty‐eight children were recruited through a follow‐up study of women who participated in a randomized controlled trial of minimal intervention vs. tight glycemic control for GDM. All participants had a fasting plasma glucose (FPG), insulin, total cholesterol, high‐density lipoprotein cholesterol (HDL‐chol), triglyceride (TG) level, and a 2‐h oral glucose tolerance test. We calculated homeostasis model assessment (HOMA) and recorded body mass index and waist circumference (WC). Criteria for metabolic syndrome for children included: FPG > 6.0 mmol/L, HDL‐chol < 1.03 mmol/L, TG > 1.24 mmol/L, WC > 90% for age and gender, and 2‐h glucose > 7.8 mmol/L. Among these children, 45 (66%), 17 (25%), 5 (7%), and 1 (1.5%) had zero, one, two, or three metabolic markers of IR, respectively. Hypertriglyceridemia (21%) was most prevalent, with no child having an elevated FPG. WC (p = 0.018) and TG (p = 0.005) were strong predictors of IR in the offspring after adjustment for age, gender, birthweight, family history, and maternal IR. Maternal and offspring HDL‐chol, TG, WC, and HOMA but not fasting or 2‐h glucose levels were significantly correlated. We conclude that metabolic markers of IR in children exposed to GDM may be present in the absence of abnormal fasting or 2‐h glucose values. Screening strategies that focus on glucose levels may need to be reconsidered to institute early intervention with lifestyle changes for children at risk.

Aging impairs heat loss, but when does it matter?

Aging is associated with an attenuated physiological ability to dissipate heat. However, it remains unclear if age-related impairments in heat dissipation only occur above a certain level of heat stress and whether this response is altered by aerobic fitness. Therefore, we examined changes in whole body evaporative heat loss (HE) as determined using whole body direct calorimetry in young (n = 10; 21 ± 1 yr), untrained middle-aged (n = 10; 48 ± 5 yr), and older (n = 10; 65 ± 3 yr) males matched for body surface area. We also studied a group of trained middle-aged males (n = 10; 49 ± 5 yr) matched for body surface area with all groups and for aerobic fitness with the young group. Participants performed intermittent aerobic exercise (30-min exercise bouts separated by 15-min rest) in the heat (40°C and 15% relative humidity) at progressively greater fixed rates of heat production equal to 300 (Ex1), 400 (Ex2), and 500 (Ex3) W. Results showed that HE was significantly lower in middle-aged untrained (Ex2: 426 ± 34; and Ex3: 497 ± 17 W) and older (Ex2: 424 ± 38; and Ex3: 485 ± 44 W) compared with young (Ex2: 472 ± 42; and Ex3: 558 ± 51 W) and middle-aged trained (474 ± 21; Ex3: 552 ± 23 W) males at the end of Ex2 and Ex3 (P < 0.05). No differences among groups were observed during recovery. We conclude that impairments in HE in older and middle-aged untrained males occur at exercise-induced heat loads of ≥400 W when performed in a hot environment. These impairments in untrained middle-aged males can be minimized through regular aerobic exercise training.

Transition of Patients with Type 2 Diabetes from Specialist to Primary Care: A Survey of Primary Care Physicians on the Usefulness of Tools for Transition

Transition from specialty to primary care for patients with type 2 diabetes has not been well studied. Stable patients may be retained in specialty clinics due to concern over the maintenance of diabetes care post-discharge, thus limiting access to specialists for new referrals. Understanding primary care physicians’ perceptions of barriers to diabetes care and the helpfulness of existing tools used in the transition back to primary care is important for facilitating the transition process. Objectives were 1) to determine the perceived helpfulness of preselected tools that could be used in the transition of patients from specialist to primary care; 2) to identify the barriers to implementation of evidence-based diabetes care from the primary care perspective; and 3) to identify the tools used currently by primary care physicians during the transition process.

Paradoxically Decreased HDL-Cholesterol Levels Associated with Rosiglitazone Therapy

Objective: To report 2 cases of very low high-density lipoprotein cholesterol (HDL-C) levels associated with rosiglitazone therapy. Case Summary: Two patients with type 2 diabetes taking rosiglitazone for glycemic control developed paradoxically low HDL-C levels during rosiglitazone therapy. In the first patient, the HDL-C level decreased from 33 to 11.6 mg/dL after 8 months of therapy. The second patients HDL-C level decreased from the baseline level of 44.8 mg/dL to 19.7 mg/dL after 4 months of rosiglitazone use. These abnormalities resolved on discontinuation of rosiglitazone and were not observed when the patients were treated with pioglitazone. The patients had no changes to other drug therapy or medical conditions known to affect lipid metabolism during treatment with rosiglitazone. Discussion: Thiazolidinediones, insulin sensitizers widely used in the treatment of type 2 diabetes, have been reported to have beneficial effects on lipids, such as triglyceride lowering and HDL-C elevation, in addition to their glucose-lowering effects. It has been suggested that rosiglitazone and pioglitazone, the 2 currently available thiazolidinediones, may differ in their effects on lipids. As of July 2006, a total of 8 cases of paradoxical lowering of plasma HDL-C associated with rosiglitazone have now been reported. Based on use of the Naranjo probability scale, the 2 cases presented here were probably associated with rosiglitazone. The duration of therapy may be important in this paradoxical effect. Conclusions: Rosiglitazone is associated with a paradoxical decrease in HDL-C levels in patients with type 2 diabetes. In patients receiving rosiglitazone, a baseline lipid panel should be performed and lipid values should be monitored during the course of therapy.