Oxidative stress, acute and regular exercise: are they really harmful in the diabetic patient?

Implications of the cGAS-STING pathway in diabetes: Risk factors and therapeutic strategies

Diabetes mellitus is an increasingly prevalent metabolic disorder characterized by chronic hyperglycemia and impaired insulin action. Although the pathogenesis of diabetes is multifactorial, emerging evidence suggests that chronic low-grade inflammation plays a significant role in the development and progression of the disease. The cyclic GMP-AMP synthase (cGAS) and its downstream signaling pathway, the stimulator of interferon genes (STING), have recently gained attention in the field of diabetes research. This article aims to provide an overview of the role of cGAS-STING in diabetes, focusing on its involvement in the regulation of immune responses, inflammation, insulin resistance, and β-cell dysfunction. Understanding the contribution of cGAS-STING signaling in diabetes may lead to the development of targeted therapeutic strategies for this prevalent metabolic disorder. The results section presents key findings from multiple studies on the impact of STING in diabetes. It discusses the influence of STING on inflammation levels within a diabetic environment, its effect on insulin resistance, and its implications for the development and progression of diabetes. The cGAS-STING signaling pathway plays a crucial role in the development and progression of diabetes.

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.

Impact of acute exercise on antioxidant enzymes activity and lipid status in blood of patients with hypertension

BACKGROUND/AIM

Many studies support the hypothesis that oxidative stress is involved in the pathogenic process of a variety of diseases including hypertension. In humans, hypertension is also considered a state of oxidative stress that can contribute to the development of arteriosclerosis and other hypertension-induced organ damage. The aim of this study was to evaluate an influence of acute physical exercise on antioxidative enzymes activity and lipid status in patients with hypertension.

METHODS

Fourty patients with hypertension and 20 age-matched controls were included in the study. To assess an influence of acute exercise on lipids and antioxidative enzymes activity the following parameters were determined at rest and immediately after the acute cardiopulmonary exercise cycloergometer test: triglycerides (TG), total cholesterol, low density cholesterol (LDL), oxidised LDL cholesterol (OxLDL), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and plasminogen activator inhibitor (PAI).

RESULTS

In basal condition, hypertensive patients compared to the control group had increased, but not significantly, level of Ox LDL (88.61 +/- 14.06 vs 79.00 +/- 29.26 mmol/L), PAI (3.06 +/- 0.56 vs 2.6 +/- 0.35 U/mL) and activity of GSH-Px (50.22 +/- 15.20 vs 44.63 +/- 13.73 U/g Hb). After acute exercise test, there was significantly greater level of Ox LDL (79.0 +/- 29.26 vs 89.3 +/- 29.07 mmol/L; p < 0.05) only in the control group. GSH-Px activity was significantly decreased only in hypertensive patients after acute exercise (50.22 +/- 15.2 vs 42.82 +/- 13.42 U/g Hb; p < 0.05), but not in the controls.

CONCLUSION

No significantly elevated Ox LDL, GSH-Px and PAI-1 levels were found in hypertensive patients during basal condition in comparison with healthy subjects. Decreased GSH-Px activity was associated with those in acute exercise only in hypertensive patients. It could be an important indicator of deficiency of physiological antioxidative defense mechanism in hypertensive patients during an acute exercise.

Exercise-induced oxidative stress and antioxidant enzyme activity in type 2 diabetic patients with and without diastolic dysfunction and hypertension

Introduction. Antioxidant systems are important factors affecting the oxidation of lipoproteins and thereby the progression of atherosclerotic disease. It has been suggested that physical activity might maintain and promote the antioxidant defence capacity against the oxidative stress. Left ventricular dysfunction (LVDD) and hypertension are more common in subjects with diabetes mellitus (DM) type 2. Objective. To evaluate the oxidative stress in patients with DM type 2, particularly with LVDD and hypertension and to determine the influence of acute exercise training on the investigated parameters. Methods. To assess the oxidative stress of patients, we determined the following antioxidative parameters: triglycerides (TG), total cholesterol, low density cholesterol, OxLDL cholesterol, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), plasminogen activator-type 1 (PAI-1) which were measured at rest and immediately after the acute bout of the cardiopulmonary exercise cycle ergometer test. Results. In basal conditions, diabetic patients had a significant increase of TG (3.12?1.09 vs 1.74?0.9 mmol/l; p<0.01), OxLDL cholesterol (84.73?16.9 vs 79.00?29.26 mmol/l; p<0.05) and SOD enzyme activity (913.38?120.36 vs 877.14 ?153.18; p<0.05) compared to controls. During the acute exercise test, there were significantly greater levels of OxLDL (84.73?16.90 vs 92.33?23.29 mmol/l; p<0.05) in study patients. SOD significantly increased in both groups during exercise, in diabetic patients (913.38?120.36 vs 921.50?130.03 U/g Hb; p<0.05) and in controls (877.14?153.18 vs 895.00?193.49 U/g Hb; p<0.05). GSH-Px significantly increased only in diabetic patients after acute exercise (45.04?11.19 vs 51.81?15.07 U/g Hb; p<0.01), but not in controls. PAI significantly decreased during the exercise test only in healthy subjects (2.60?0.35 vs 2.22?0.65; p<0.05). Type 2 diabetic patients with cardiovascular complications (LVDD and hypertension) had a significant increase of GSH-Px activity (47.10?7.37 vs 54.52?11.97 U/g Hb; p<0.01). Conclusion. Elevated enzyme levels are associated with exercise in type 2 diabetic patients. We suggest that it could be a compensatory mechanism to prevent free radical tissue damage. We hypothesize that a physical training programme induces the enhancement of muscular and liver antioxidant enzymes and reduces the oxidative stress.

Clinical evaluation of oxidative stress in patients with diabetes mellitus type II: Impact of acute exercise

Background/Aim. Exercise is a well recognized model of oxidative stress and, also, an important tool in diabetes management. The aim of our study was to evaluate oxidative stress in patients with diabetes mellitus type 2 and to determine influence of acute exercise training on the investigated parameters. Methods. To evaluate oxidative stress in the patients, we determinated following parameters: triglycerides (TG), total cholesterol, low density lipoprotein cholesterol (LDL), oxidized LDL cholesterol (Ox LDL), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), plasminogen activator inhibitor (PAI) which were measured at rest and immediately after the acute bout of cardiopulmonary exercise cycle-ergometer test. Results. In basal condition, diabetic patients compared to controls have significant higher values of TG (3.12 ? 1.09 vs 1.74 ? 0.9 mmol/L, p < 0.01), Ox LDL (84.73 ? 16.90 vs 79.00 ? 29.26 mmol/L, p < 0.05) and SOD enzyme activity (913.38 ? 120.36 vs 877.14 ? 153.18 U/g Hb, p < 0.05). During the acute exercise test, there was significant increase of Ox LDL in both the study patients (from 84.73 ? 16.90 to 92.33 ? 23.29 mmol/L, p < 0.05) and in the control group (from 79.00 ? 29.26 to 89.30 ? 29.07 mmol/L, p < 0.05). SOD activity was significantly increased in both groups during exercise, in diabetic patients from 913.38 ? 120.36 to 921.50 ? 130.03 U/gHb, p < 0.05, and in the controls from 877.14 ? 153.18 to 895.00 ? 193.49, U/gHb, p < 0.05. GSH-Px activity was significantly increased only in the diabetic patients after the acute exercise (from 45.04 ? 11.19 to 51.81 ? 15.07 U/gHb, p < 0.01), but not in the controls (from 44.63 ? 13.73 to 43.97 ? 25.97 U/gHb, p = ns). PAI significantly decreased during the exercise test, only in the healthy subjects (from 2.60 ? 0.35 to 2.22 ? 0.65, p < 0.05). Type 2 diabetic patients with complications had only significant increase in GSH-Px activity (from 47.10 ? 7.37 to 54.52 ? 11.97 U/gHb, p < 0.01). Conclusion. Elevated Ox LDL, SOD and GSH-Px levels are associated with acute exercise in type 2 diabetic patients. We suggest that it could be a compensatory mechanism to preventing free radicals tissue damage. We hypothesize that a physical training program induces an enhance of muscular and liver antioxidant enzymes activity and reduces oxidative stress. Further studies are needed to explore the relationship between exercise and antioxidant system in diabetic patients with and without complications.

A single session of resistance exercise induces oxidative damage in untrained men

PURPOSE

During exercise, the production of reactive oxygen and nitrogen species significantly increases. The aim of the present study was to investigate the effects of a single session of resistance exercise on antioxidant capacity, oxidative damage, and inflammation.

METHODS

Muscle biopsies, urine, and blood samples were collected from seven healthy men before and after a single bout of resistance exercise.

RESULTS

A single session of resistance exercise was found to induce oxidative damage, as shown by a 40% increase in the concentration of urinary F2alpha-isoprostanes (P < 0.05). Total antioxidant capacity of plasma increased 16% (P < 0.05). This increase seemed to be predominantly attributable to an increase in plasma uric acid concentrations of 53% (P < 0.05). Similar to uric acid, but to a relatively much smaller extent, vitamin C and vitamin E levels in plasma were also elevated (P < 0.05). Moreover, the erythrocyte glutathione (GSH) [corrected] concentration increased 47% during exercise (P < 0.05). Also in skeletal muscle, uric acid levels were found to increase after exercise (P < 0.05). Moreover, 30 min after exercise, skeletal muscle glutathione S-transferase (GST) and glutathione reductase activity increased 28 and 42%, respectively (P < 0.05). Skeletal muscle reduced GSH [corrected] and GSH [corrected] disulphide (GSSG) concentrations were not affected by exercise. The Nuclear Factor kappa B (NF-kappaB) activity in peripheral blood mononuclear cells (PBMC) was not increased by exercise, indicating that a NF-kappaB-mediated inflammatory response does not occur.

CONCLUSION

We conclude that a single session of resistance exercise induces oxidative damage despite an adaptive increase in antioxidant capacity of blood and skeletal muscle.

Hemodynamic and oxidative stress profile after exercise in type 2 diabetes

This study investigated the effect of an acute bout of exercise (>85% VO2Max) on biochemical, hemodynamic and oxidative stress variables in sedentary and physically active subjects with type 2 diabetes (T2D). Blood measurements were taken before and after a treadmill test on 12 sedentary non-diabetes subjects (ND), 12 sedentary type 2 diabetes (T2S) and 9 physically active T2D subjects (T2DA). T2DS subjects before and after the treadmill test showed a higher plasma glucose (123.2 +/- 19.0 mg/dL versus 108.9 +/- 16.8 mg/dL, p < 0.001), HbA1C (8.7 +/- 2.4% versus 7.3 +/- 1.2%, p < 0.001) and body fat% (21.3 +/- 5.7% versus 34.6 +/- 4.5%, p < 0.001) than T2DA subjects. T2DA had higher VO2Max (37.7 +/- 3.5 versus 29.5 +/- 3.2, p < 0.05), time on treadmill (22.3 +/- 2.1 min versus 16.1 +/- 2.1 min, p < 0.05), hemoglobin (17.9 +/- 0.9 g/dL, p < 0.05) and lower blood pressure levels in comparison to ND and T2DS subjects. Thiobarbituric acid substances (TBARS) in T2DS were higher than in T2DA subjects (0.27 +/- 0.1 nmol/mL versus 0.21 +/- 0.1 nmol/mL, p < 0.05). Glutathione (GSH) levels were similar among the groups. Physically active type 2 diabetes subjects had a more favorable biochemical, hemodynamic and oxidative stress profile than sedentary subjects. The coexistence of a poor cardiopulmonary performance and high oxidative stress environment can determine a profile of high risk for serious cardiovascular events in patients with diabetes.

Obesity Exacerbates Oxidative Stress Levels after Acute Exercise

INTRODUCTION/PURPOSE

This study compared oxidative stress levels and antioxidant capacity in nonobese and obese participants after acute resistance (RX) and aerobic exercise (AX).

METHODS

Blood samples were collected from 28 nonobese (mean = 20.8% body fat) and obese (mean = 35.0% body fat) participants pre- and immediately post-RX and AX. Lipid hydroperoxides (PEROX), malondialdehyde (TBARS) and total antioxidant status (TAS) were measured. Oxygen consumption (VO2) and minute ventilation (VE) values were determined during each exercise session.

RESULTS

In both groups, PEROX and TBARS were elevated post-RX and AX, with the greater elevations occurring in the obese group in each case (P < 0.05). In the obese, TBARS increased by 42% and 41% post-RX and AX, respectively, compared with 7.1% and 26.9% in the nonobese group. PEROX increased by 100% and 70% post-RX and AX, respectively, in the obese, and by 85% and 62% in the nonobese. TAS was 17% higher (P < 0.05) post-RX in the nonobese compared with the obese, whereas TAS values were not different post-AX. Peak and average VE, and relative VO2). rates were higher in the obese post-AX compared with the nonobese (P < 0.05) Correlations existed between the exercise-induced change in PEROX and body fat, vitamin C and A intake, peak oxygen consumption, and exercise ventilation rates in the obese group (r = 0.784-0.776, P < 0.05). In both groups, the exercise-induced changes in PEROX were associated with vitamin C intake, exercise ventilation rates, VO2peak, and plasma triglycerides (r = 0.669-0.558, P < 0.05).

CONCLUSION

Lipid peroxidation is elevated in both RX and AX, and it is exacerbated in the obese. The mechanisms underlying this response in each exercise may be different but could involve plasma triglycerides, oxygen consumption, and antioxidant intake.

Diet and exercise in type 2 diabetes mellitus

The question is no longer whether diet and exercise can benefit the individual with type 2 diabetes. Rather, the type and duration of exercise the magnitude of the effects on glycemic control, insulin sensitivity, and on risk factors for cardiovascular disease must be considered in determining the feasibility and acceptability of an intervention program. It is now clear that regular physical exercise is important in both the prevention and treatment of type 2 diabetes. The benefits of exercise are many and include increased energy expenditure, which, combined with dietary restriction, leads to decreased body fat, increased insulin sensitivity, improved long-term glycemic control, improved lipid profiles, lower blood pressure, and increased cardiovascular fitness. Persons with type 2 diabetes often find it difficult to exercise and are at increased risk for injury or exacerbation of underlying diseases or diabetic complications. Therefore, before starting an exercise program, all patients with type 2 diabetes should have a complete history and physical examination, with particular attention to evaluation of cardiovascular disease, medications that may affect glycemic control during or after exercise, and diabetic complications including retinopathy, nephropathy, and neuropathy. Exercise programs should be designed to start slowly, build up gradually, and emphasize moderately intense exercise performed at least three times a week and preferably five to seven times a week for best results.