Athletes with IDDM exhibit impaired metabolic control and increased lipid utilization with no increase in insulin sensitivity

Relationship Between Moderate-to-Vigorous Physical Activity and Glycemia Among Young Adults with Type 1 Diabetes and Overweight or Obesity: Results from the Advancing Care for Type 1 Diabetes and Obesity Network (ACT1ON) Study

Aims: Using data from the ACT1ON study, we conducted secondary analyses to assess the relationship between minutes of moderate-to-vigorous physical activity (MVPA) and glycemia in adults with type 1 diabetes (T1D) and overweight or obesity. Materials and Methods: Participants (n = 66) with T1D provided measures of glycemia (hemoglobin A1c [HbA1c], percent of time below range <70 mg/dL, time-in-range [TIR 70-180 mg/dL], and time above range [TAR >180 mg/dL]) and self-reported physical activity (Global Physical Activity Questionnaire [GPAQ] and Previous Day Physical Activity Recalls [PDPAR]) at baseline, 3, 6, and 9 months postintervention. Wearable activity data were available for a subset of participants (n = 27). Associations were estimated using mixed effects regression models adjusted for design, demographic, clinical, and dietary covariates. Results: Among young adults 19-30 years of age with a baseline HbA1c of 7.9% ± 1.4% and body mass index of 30.3 (interquartile range 27.9, 33.8), greater habitual weekly MVPA minutes were associated with higher HbA1c through the GPAQ (P < 0.01) and wearable activity data (P = 0.01). We did not observe a significant association between habitual MVPA and any continuous glucose monitoring metrics. Using PDPAR data, however, we observed that greater daily MVPA minutes were associated with more TAR (P < 0.01) and reduced TIR (P < 0.01) on the day following reported physical activity. Conclusions: Among young adults with T1D and overweight or obesity, increased MVPA was associated with worsened glycemia. As physical activity is vital to cardiovascular health and weight management, additional research is needed to determine how to best support young adults with T1D and overweight or obesity in their efforts to increase physical activity. Clinical Trial Registration number: NCT03651622.

Association of HbA1c with VO2max in Individuals with Type 1 Diabetes: A Systematic Review and Meta-Analysis

The aim of this systematic review and meta-analysis was to evaluate the association between glycemic control (HbA1c) and functional capacity (VO2max) in individuals with type 1 diabetes (T1DM). A systematic literature search was conducted in EMBASE, PubMed, Cochrane Central Register of Controlled Trials, and ISI Web of Knowledge for publications from January 1950 until July 2020. Randomized and observational controlled trials with a minimum number of three participants were included if cardio-pulmonary exercise tests to determine VO2max and HbA1c measurement has been performed. Pooled mean values were estimated for VO2max and HbA1c and weighted Pearson correlation and meta-regression were performed to assess the association between these parameters. We included 187 studies with a total of 3278 individuals with T1DM. The pooled mean HbA1c value was 8.1% (95%CI; 7.9−8.3%), and relative VO2max was 38.5 mL/min/kg (37.3−39.6). The pooled mean VO2max was significantly lower (36.9 vs. 40.7, p = 0.001) in studies reporting a mean HbA1c > 7.5% compared to studies with a mean HbA1c ≤ 7.5%. Weighted Pearson correlation coefficient was r = −0.19 (p < 0.001) between VO2max and HbA1c. Meta-regression adjusted for age and sex showed a significant decrease of −0.94 mL/min/kg in VO2max per HbA1c increase of 1% (p = 0.024). In conclusion, we were able to determine a statistically significant correlation between HbA1c and VO2max in individuals with T1DM. However, as the correlation was only weak, the association of HbA1c and VO2max might not be of clinical relevance in individuals with T1DM.

An ultra-compact and wireless tag for battery-free sweat glucose monitoring

Glucose monitoring before, during, and after exercise is essential for people with diabetes as exercise increases the risk of activity-induced hyper- and hypo-glycemic events. The situation is even more challenging for athletes with diabetes as they have impaired metabolic control compared to sedentary individuals. In this regard, a compact and noninvasive wearable glucose monitoring device that can be easily worn is critical to enabling glucose monitoring. This report presents an ultra-compact glucose tag with a footprint and weight of 1.2 cm² and 0.13 g, respectively, for sweat analysis. The device comprises a near field communication (NFC) chip, antenna, electrochemical sensor, and microfluidic channels implemented in different material layers. The device has a flexible and conformal structure and can be easily attached to different body parts. The battery-less operation of the device was enabled by NFC-based wireless power transmission and the compact antenna. Femtosecond laser ablation was employed to fabricate a highly compact and flexible NFC antenna. The proposed device demonstrated excellent operating characteristics with a limit of detection (LOD), limit of quantification (LOQ), and sensitivity of 24 μM, 74 μM, and 1.27 μA cm^-2 mM^-1, respectively. The response of the proposed sensor in sweat glucose detection and quantification was validated by nuclear magnetic resonance spectroscopy (NMR). Also, the device's capability in attachment to the body, sweat collection, and glucose measurement was demonstrated through in vitro and in vivo experiments, and satisfactory results were obtained.

American Medical Society for Sports Medicine Position Statement on the Care of the Athlete and Athletic Person With Diabetes

ABSTRACT

The American Medical Society for Sports Medicine (AMSSM) developed this position statement to assist physicians and other health professionals in managing athletes and active people with diabetes. The AMSSM selected the author panel through an application process to identify members with clinical and academic expertise in the care of active patients with diabetes. This article reviews the current knowledge and gaps regarding the benefits and risks of various types of exercise and management issues for athletes and physically active people with diabetes, including nutrition and rehabilitation issues. Resistance exercises seem to be beneficial for patients with type 1 diabetes, and the new medications for patients with type 2 diabetes generally do not need adjustment with exercise. In preparing this statement, the authors conducted an evidence review and received open comment from the AMSSM Board of Directors before finalizing the recommendations.

Beneficial Effects of Physical Activity in Diabetic Patients

One of the main goals of diabetic therapy is to achieve the best metabolic control to prevent the development and progression of potential complications. A multidisciplinary approach characterized by the combination of diet, physical activity (PA) and drug therapy with oral and injectable (non-insulin) pharmacological agents, is desirable to optimize metabolic control. The aim of this review is to explain the contribution of PA and its beneficial effects on patients affected by type 1 (T1D) and type 2 diabetes (T2D). We provide an overview of evidence on the effects of PA for the main two types of diabetes mellitus (DM) to identify the right level of PA to be recommended. We discuss the physiological and clinical role of PA in people with DM. It can be concluded that the objective of antidiabetic therapy should be the achievement and optimization of metabolic control through a multidisciplinary approach involving non-pharmacological therapy such as diet and PA, which has a crucial role.

Exercise and type 1 diabetes (T1DM)

Physical exercise is firmly incorporated in the management of type 1 diabetes (T1DM), due to multiple recognized beneficial health effects (cardiovascular disease prevention being preeminent). When glycemic values are not excessively low or high at the time of exercise, few absolute contraindications exist; practical guidelines regarding amount, type, and duration of age-appropriate exercise are regularly updated by entities such as the American Diabetes Association and the International Society for Pediatric and Adolescent Diabetes. Practical implementation of exercise regimens, however, may at times be problematic. In the poorly controlled patient, specific structural changes may occur within skeletal muscle fiber, which is considered by some to be a disease-specific myopathy. Further, even in well-controlled patients, several homeostatic mechanisms regulating carbohydrate metabolism often become impaired, causing hypo- or hyperglycemia during and/or after exercise. Some altered responses may be related to inappropriate exogenous insulin administration, but are often also partly caused by the "metabolic memory" of prior glycemic events. In this context, prior hyperglycemia correlates with increased inflammatory and oxidative stress responses, possibly modulating key exercise-associated cardio-protective pathways. Similarly, prior hypoglycemia correlates with impaired glucose counterregulation, resulting in greater likelihood of further hypoglycemia to develop. Additional exercise responses that may be altered in T1DM include growth factor release, which may be especially important in children and adolescents. These multiple alterations in the exercise response should not discourage physical activity in patients with T1DM, but rather should stimulate the quest for the identification of the exercise formats that maximize beneficial health effects.

Patients with type 1 diabetes oxidize fat at a greater rate than age- and sex-matched controls

INTRODUCTION

Elevated patient blood glucose and exogenous insulin administration may affect substrate oxidation in patients with type 1 diabetes mellitus (T1DM); however, this has not been demonstrated with conviction. We examined substrate oxidation during incremental exercise in a group of subjects with T1DM and compared the results to those of an age- and sex-matched control group of subjects.

METHODS

A group of subjects with T1DM (n = 29; 10 men, 19 women) was recruited for metabolic testing from a weeklong fitness camp. An age- and sex-matched control group of subjects (n = 29; 10 men, 19 women) was recruited from the local community. Subjects were required to avoid strenuous exercise for 48 hours and fast for 2 hours prior to metabolic testing. An incremental test to exhaustion on either a stationary cycle or treadmill was administered to all subjects. Maximum oxygen consumption of subjects was measured (T1DM subjects: 41.4 ± 1.9 mL/kg/min; control subjects: 48.4 ± 1.3 mL/kg/min). Blood glucose was recorded at 20 and 5 minutes before the exercise test, and at 5 and 20 minutes after the exercise test.

RESULTS

The T1DM and control subjects were matched for age, height, weight, and body composition. Subject blood glucose levels were higher in the group of subjects with T1DM than the control group at all times measured (P < 0.001). At all relative intensities of exercise (50%-80% maximum oxygen consumption; P < 0.050), absolute fat oxidation was higher in the group of subjects with T1DM (P < 0.050) and absolute carbohydrate oxidation was higher in the control group.

CONCLUSION

Our data indicate that subjects with T1DM oxidize fat at a higher rate and carbohydrates at a lower rate when compared with age- and sex-matched controls at the same relative intensity of exercise, despite the elevated pre-exercise blood glucose of subjects with T1DM.

Exercise and glucose metabolism in persons with diabetes mellitus: perspectives on the role for continuous glucose monitoring

Exercise causes profound changes in glucose homeostasis. For people with type 1 diabetes, aerobic exercise usually causes blood glucose concentration to drop rapidly, while anaerobic exercise may cause it to rise, thereby making glycemic control challenging. Having the capacity to know their glucose levels and the direction of change during exercise increases self-efficacy in these persons who are prone to hypo- and hyperglycemia. For people with type 2 diabetes, learning first hand that regular exercise improves glucose levels may be a motivating factor in getting them to be more active. Continuous glucose monitoring is a potentially useful adjunct to diabetes management for the active person with either forms of diabetes. This review aims to guide the reader to use this technology to its maximum advantage by providing an overview of technical features, performance characteristics, and clinical utility, all balanced against the limitations that may be more prominent during physical activity.

Exercise capacity in subjects with type 1 diabetes mellitus in eu- and hyperglycaemia

BACKGROUND

Circumstantial evidence suggests that an increase in plasma glucose availability improves exercise capacity in subjects with type 1 diabetes mellitus. The aim of this study was to assess exercise capacity in eu- and hyperglycaemic conditions in subjects with type 1 diabetes.

METHODS

Eight moderately exercise-trained male subjects with type 1 diabetes on continuous subcutaneous insulin infusion were studied. Using identical insulin infusion rates, the patients were randomly allocated to perform two stepwise ergometer tests in eu- and hyperglycaemic clamp conditions. The primary endpoint was the peak power output; the secondary endpoints comprised the rate of perceived exertion, lactate levels, heart rate, and respiratory exchange ratio.

RESULTS

Eu- and hyperglycaemic clamp conditions were observed at a plasma glucose concentration of 5.3 +/- 0.6 mmol/L and 12.4 +/- 2.1 mmol/L, respectively (mean +/- SD), and remained stable throughout the physical exercise. Insulin levels were similar in both conditions. Hyperglycaemia did not result in a significant increase in the peak power output compared to euglycaemia (mean paired difference of 4.96 W, 95% CI - 11.3 to 21.2, p = 0.49). Hyperglycaemia did not have a significant impact on the secondary endpoints compared to euglycaemia. Sensitivity analyses confirmed these results.

CONCLUSIONS

In subjects with type 1 diabetes, exercise capacity is not influenced by hyperglycaemia. Comparable levels of lactate and similar respiratory exchange ratio suggest that an increase in extracellular glucose availability did not translate into increased intracellular glucose oxidation.

Dyslipidemia and a reversible decrease in insulin sensitivity induced by therapy with 13-cis-retinoic acid

BACKGROUND

13-cis-Retinoic acid (Roaccutan) treatment is associated with disturbances in lipid and sometimes also in glucose metabolism. Thus, we investigated whether 13-cis-retinoic acid treatment decreases insulin sensitivity.

METHODS

We studied 11 men [aged 24+/-2 years (mean+/-SEM), body mass index (BMI) 22.1+/-0.9 kg/m(2)] who received Roaccutan treatment for acne for a period averaging 5 months but who were otherwise healthy. The insulin sensitivity of the subjects was measured before, during and 1-3 months after the end of treatment using the euglycaemic hyperinsulinaemic clamp technique.

RESULTS

Treatment with 13-cis-retinoic acid reduced total (59+/-4 vs 55+/-4 micromol/kg/min, p<0.02), oxidative (25+/-1 vs 22+/-2 micromol/kg/min, p<0.05) and non-oxidative (36+/-3 vs 33+/-3 micromol/kg/min, p=0.05) glucose disposal rate, and there was a 4% increase in HbA(1c) (from 5.2+/-0.07 to 5.4+/-0.07%, p<0.02). After treatment cessation these values returned to baseline. 13-cis-Retinoic acid treatment also resulted in increased very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol, increased VLDL triglyceride, and increased VLDL and LDL phospholipid concentrations.

CONCLUSION

Treatment of acne with 13-cis-retinoic acid reduces insulin sensitivity and induces alterations in lipid metabolism resembling those of the insulin resistance syndrome.

Plasma acylation stimulating protein concentration and subcutaneous adipose tissue C3 mRNA expression in nondiabetic and type 2 diabetic men

We studied the effect of an oral fat load on plasma acylation stimulating protein (ASP) concentrations in 9 lean healthy (age 59+/-2 years, body mass index [BMI] 23.2+/-0.4 kg/m(2); both mean+/-SEM), 9 obese nondiabetic (58+/-2 years, BMI 29.4+/-0.5 kg/m(2)), and 12 type 2 diabetic (60+/-2 years, BMI 29.6+/-1.0 kg/m(2)) men. Because ASP is a cleavage product of complement protein C3 (C3adesArg) and its secretion is regulated by insulin, we also examined the subcutaneous adipose tissue expression of C3 mRNA before and after a 240-minute euglycemic hyperinsulinemic clamp in a subgroup of these men. Plasma ASP concentration and adipose tissue C3 mRNA expression were higher in the obese groups than in the lean men. Plasma ASP concentration did not change significantly after the fat load. Fasting plasma ASP concentration and C3 mRNA expression were correlated negatively with insulin sensitivity and positively with the magnitude of postprandial lipemia in nondiabetic but not in type 2 diabetic men. The expression of C3 mRNA was not regulated by insulin. These data suggest that ASP is associated with whole-body glucose and lipid metabolism in nondiabetic individuals, whereas metabolic disturbances in diabetes may overcome the regulatory role of ASP in lipid and glucose metabolism.

Fatty acid transport protein-1 mRNA expression in skeletal muscle and in adipose tissue in humans

Fatty acid transporter protein (FATP)-1 mRNA expression was investigated in skeletal muscle and in subcutaneous abdominal adipose tissue of 17 healthy lean, 13 nondiabetic obese, and 16 obese type 2 diabetic subjects. In muscle, FATP-1 mRNA levels were higher in lean women than in lean men (2.2 +/- 0.1 vs. 0.6 +/- 0.2 amol/microg total RNA, P < 0.01). FATP-1 mRNA expression was decreased in skeletal muscle in obese women both in nondiabetic and in type 2 diabetic patients (P < 0.02 vs. lean women in both groups), and in all women there was a negative correlation with basal FATP-1 mRNA level and body mass index (r = -0.74, P < 0.02). In men, FATP-1 mRNA was expressed at similar levels in the three groups both in skeletal muscle (0.6 +/- 0.2, 0.6 +/- 0.2, and 0.8 +/- 0.2 amol/microg total RNA in lean, obese, and type 2 diabetic male subjects) and in adipose tissue (0.9 +/- 0.2 amol/microg total RNA in the 3 groups). Insulin infusion (3 h) reduced FATP-1 mRNA levels in muscle in lean women but not in lean men. Insulin did not affect FATP-1 mRNA expression in skeletal muscle in obese nondiabetic or in type 2 diabetic subjects nor in subcutaneous adipose tissue in any of the three groups. These data show a gender-related difference in the expression of the fatty acid transporter FATP-1 in skeletal muscle of lean individuals and suggest that changes in FATP-1 expression may not contribute to a large extent to the alterations in fatty acid uptake in obesity and/or type 2 diabetes.

Subcutaneous adipose tissue expression of plasminogen activator inhibitor-1 (PAI-1) in nondiabetic and Type 2 diabetic subjects

OBJECTIVE

Increased plasma levels of plasminogen activator inhibitor-1 (PAI-1) have been suggested to be a part of the insulin resistance syndrome, and recent data suggest that adipose tissue participates in the production of PAI-1. We examined the expression and insulin regulation of subcutaneous adipose tissue PAI-1 mRNA and its relationship to insulin sensitivity.

DESIGN

A cross-sectional study involving five lean (60.0+/-3.1 years, BMI 23.5+/-0.5 kg/m(2)) and six obese nondiabetic men (56.0+/-3.1 years, BMI 30.4+/-0.7 kg/m(2)), and six obese Type 2 diabetic men (61.4+/-3.2 years, BMI 31.8+/-1.0 kg/m(2)).

MEASUREMENTS

Subcutaneous adipose tissue PAI-1 mRNA and insulin sensitivity were quantified using RT-competitive PCR and euglycemic hyperinsulinemic clamp technique, respectively.

RESULTS

Subcutaneous adipose tissue PAI-1 mRNA levels were higher in obese nondiabetic and Type 2 diabetic men than in lean nondiabetic men. PAI-1 mRNA levels decreased in the three groups during a 240-min euglycemic hyperinsulinemic clamp (P<0.05 for all groups), and a similar reduction was observed during a 240-min saline control study indicating that adipose tissue PAI-1 gene expression has diurnal variation and is not acutely controlled by hyperinsulinemia. The basal PAI-1 mRNA levels correlated positively with BMI, and waist-to-hip ratio; and negatively with whole-body glucose disposal rate in nondiabetic men.

CONCLUSIONS

Subcutaneous adipose tissue PAI-1 mRNA expression is increased in obese nondiabetic or in Type 2 diabetic men. Subcutaneous adipose tissue PAI-1 mRNA expression is increased in proportion to visceral obesity and to the level of whole-body insulin resistance. Subcutaneous adipose tissue PAI-1 mRNA expression is not acutely regulated by insulin, and it is subject to a diurnal variation.

Subcutaneous adipose tissue expression of tumour necrosis factor-alpha is not associated with whole body insulin resistance in obese nondiabetic or in type-2 diabetic subjects

BACKGROUND

An association with subcutaneous adipose tissue TNFalpha expression and insulin resistance has been suggested in obesity/type-2 diabetes, but this has not been examined directly. In the first part of the study we investigated whether this association is present in 7 lean, 10 obese nondiabetic and 9 type-2 diabetic men. In the second part of the study we examined the relationship between adipose tissue TNFalpha mRNA levels and BMI in 81 nondiabetic subjects spanning a wide range of BMIs.

METHODS

Subcutaneous adipose tissue TNFalpha mRNA levels and insulin sensitivity were determined with quantitative RT-competitive PCR and hyperinsulinaemic clamp, respectively.

RESULTS

Subcutaneous adipose tissue TNFalpha mRNA levels were similar in 7 lean and 10 obese nondiabetic and 9 type-2 diabetic men (P = 0.68), and did not change in response to 240-min hyperinsulinaemia. TNFalpha mRNA levels and insulin sensitivity were not correlated. Unexpectedly, no correlation between TNFalpha mRNA and BMI was found. The relationship between adipose tissue TNFalpha mRNA and BMI was examined further in 31 male and 50 female nondiabetic subjects. The subcutaneous adipose tissue TNFalpha mRNA level correlated with BMI in all subjects (rS = 0.32, P < 0.01), and in a subgroup analysis in men (rS = 0.55, P < 0.01) but not in women (rS = - 0.08). The correlation in men was dependent on a fourfold higher TNFalpha mRNA level in 5 morbidly obese men while there was no difference in TNFalpha mRNA levels in lean or obese men.

CONCLUSIONS

Subcutaneous adipose tissue TNFalpha expression does not correlate with insulin sensitivity in nondiabetic or type-2 diabetic men; is not regulated by acute hyperinsulinaemia; and is increased only in morbidly obese men.

Exercise and diabetes control: a winning combination

It is becoming evident that in many individuals, diabetes of all types can be precipitated or exacerbated by inactivity. Exercise is a cornerstone in diabetes management and conveys many health benefits. Different forms of exercise can have varying effects on the blood sugar response, especially in individuals using insulin. Appropriate exercise for effective management of blood sugar levels and published clinical exercise recommendations for individuals with type 1 and type 2 diabetes include additional blood glucose monitoring, modified insulin doses, and supplemental carbohydrate intake. Physicians who treat exercising patients with diabetes should tailor programs to meet individual requirements.

Intact insulin stimulation of skeletal muscle blood flow, its heterogeneity and redistribution, but not of glucose uptake in non-insulin-dependent diabetes mellitus

We tested the hypothesis that defects in insulin stimulation of skeletal muscle blood flow, flow dispersion, and coupling between flow and glucose uptake contribute to insulin resistance of glucose uptake in non-insulin-dependent diabetes mellitus (NIDDM). We used positron emission tomography combined with [15O]H2O and [18F]-2-deoxy--glucose and a Bayesian iterative reconstruction algorithm to quantitate mean muscle blood flow, flow heterogeneity, and their relationship to glucose uptake under normoglycemic hyperinsulinemic conditions in 10 men with NIDDM (HbA1c 8.1+/-0.5%, age 43+/-2 yr, BMI 27.3+/-0.7 kg/m2) and in 7 matched normal men. In patients with NIDDM, rates of whole body (35+/-3 vs. 44+/-3 micromol/kg body weight.min, P < 0.05) and femoral muscle (71+/-6 vs. 96+/-7 micromol/kg muscle.min, P < 0.02) glucose uptake were significantly decreased. Insulin increased mean muscle blood flow similarly in both groups, from 1.9+/-0.3 to 2.8+/-0.4 ml/100 g muscle.min in the patients with NIDDM, P < 0.01, and from 2.3+/-0.3 to 3.0+/-0.3 ml/100 g muscle.min in the normal subjects, P < 0.02. Pixel-by-pixel analysis of flow images revealed marked spatial heterogeneity of blood flow. In both groups, insulin increased absolute but not relative dispersion of flow, and insulin-stimulated but not basal blood flow colocalized with glucose uptake. These data provide the first evidence for physiological flow heterogeneity in human skeletal muscle, and demonstrate that insulin increases absolute but not relative dispersion of flow. Furthermore, insulin redirects flow to areas where it stimulates glucose uptake. In patients with NIDDM, these novel actions of insulin are intact, implying that muscle insulin resistance can be attributed to impaired cellular glucose uptake.