Oxidative Stress in Patients with Type 1 Diabetes Mellitus: Is It Affected by a Single Bout of Prolonged Exercise?

Presently, no clear-cut guidelines are available to suggest the more appropriate physical activity for patients with type 1 diabetes mellitus due to paucity of experimental data obtained under patients' usual life conditions. Accordingly, we explored the oxidative stress levels associated with a prolonged moderate intensity, but fatiguing, exercise performed under usual therapy in patients with type 1 diabetes mellitus and matched healthy controls. Eight patients (4 men, 4 women; 49\ub111 years; Body Mass Index 25.0\ub13.2 kg\ub7m-2; HbA1c 57\ub110 mmol\ub7mol -1) and 14 controls (8 men, 6 women; 47\ub111 years; Body Mass Index 24.3\ub13.3 kg\ub7m-2) performed a 3-h walk at 30% of their heart rate reserve. Venous blood samples were obtained before and at the end of the exercise for clinical chemistry analysis and antioxidant capacity. Capillary blood samples were taken at the start and thereafter every 30 min to determine lipid peroxidation. Patients showed higher oxidative stress values as compared to controls (95.9\ub19.7 vs. 74.1\ub112.2 mg\ub7L -1 H2O2; p<0.001). In both groups, oxidative stress remained constant throughout the exercise (p = NS), while oxidative defence increased significantly at the end of exercise (p<0.02) from 1.16\ub10.13 to 1.19\ub10.10 mmol\ub7L-1 Trolox in patients and from 1.09\ub10.21 to 1.22\ub10.14 mmol\ub7L -1 Trolox in controls, without any significant difference between the two groups. Oxidative stress was positively correlated to HbA1c (p<0.005) and negatively related with uric acid (p<0.005). In conclusion, we were the first to evaluate the oxidative stress in patients with type 1 diabetes exercising under their usual life conditions (i.e. usual therapy and diet). Specifically, we found that the oxidative stress was not exacerbated due to a single bout of prolonged moderate intensity aerobic exercise, a condition simulating several outdoor leisure time physical activities. Oxidative defence increased in both patients and controls, suggesting beneficial effects of prolonged aerobic fatiguing exercis

Prolonged exercise in type 1 diabetes: performance of a customizable algorithm to estimate the carbohydrate supplements to minimize glycemic imbalances

Physical activity in patients with type 1 diabetes (T1DM) is hindered because of the high risk of glycemic imbalances. A recently proposed algorithm (named Ecres) estimates well enough the supplemental carbohydrates for exercises lasting one hour, but its performance for prolonged exercise requires validation. Nine T1DM patients (5M/4F; 35-65 years; HbA1c 54 \ub1 13 mmol \ub7 mol(-1)) performed, under free-life conditions, a 3-h walk at 30% heart rate reserve while insulin concentrations, whole-body carbohydrate oxidation rates (determined by indirect calorimetry) and supplemental carbohydrates (93% sucrose), together with glycemia, were measured every 30 min. Data were subsequently compared with the corresponding values estimated by the algorithm. No significant difference was found between the estimated insulin concentrations and the laboratory-measured values (p = NS). Carbohydrates oxidation rate decreased significantly with time (from 0.84 \ub1 0.31 to 0.53 \ub1 0.24 g \ub7 min(-1), respectively; p < 0.001), being estimated well enough by the algorithm (p = NS). Estimated carbohydrates requirements were practically equal to the corresponding measured values (p = NS), the difference between the two quantities amounting to -1.0 \ub1 6.1 g, independent of the elapsed exercise time (time effect, p = NS). Results confirm that Ecres provides a satisfactory estimate of the carbohydrates required to avoid glycemic imbalances during moderate intensity aerobic physical activity, opening the prospect of an intriguing method that could liberate patients from the fear of exercise-induced hypoglycemia

Comparison of ECRES Algorithm with Classical Method in Management of Diabetes Type 1 Exercise-Related Imbalances

Nutrition and physical activity are important parts of a healthy lifestyle and management of diabetes. Regular moderate-intensity physical activity in type 1 diabetes patients can enhance insulin sensitivity, reduce the risk of cardiovascular disease and improve psychological well-being. Nevertheless, the risk of exercise-induced hypoglycemia is a great challenge for patients with type 1 diabetes and represents an important barrier to physical activity in these patients. Recently, an algorithm called ECRES has been developed with the aim of estimating, depending on patient\u2019s own therapy and specific physical activity, the glucose supplement required by the patient to maintain safe blood glucose levels. The aim of this study is to compare the ECRES algorithm to classical quantitative approach. Therefore, we measured and compared glycaemia in 23 patients (mean age: 43 \ub1 12 years) during 1-h treadmill walk/run maintaining heart rate at 65% of his/her theoretical maximum value for age. For each subject two separate tests were performed: with carbohydrates supplement estimated by ECRES algorithm and by classical approach, respectively. The average heart rate observed during exercise (average progression speed: 5.8 \ub1 0.8 km/h at 4.2 \ub1 2.3% inclination) was 111.5 \ub1 9.4 bpm. Glycaemia measured by portable glucometer showed no significant differences between tests managed with ECRES algorithm and with classical approach, both before (149 \ub1 47 vs. 128 \ub1 41 mg/dL) and at the end of the performed exercise (134 \ub1 66 vs. 138 \ub1 54 mg/dL). The ECRES algorithm, however, estimated a significantly lower amount of carbohydrate needed for physical activity as compared to that suggested by the classical approach (14.8 \ub1 12.0 g vs. 23.4 \ub1 4.7 g; p < 0.05), while maintaining patients\u2019 blood glucose within optimal clinical limits. The study results confirmed the validity of the estimates made by the ECRES algorithm

Relationship between oxidative stress and HbA_1c or uric acid.

<p>Panel A. Relationship between baseline HbA_1c values (mmol·mol⁻¹) and oxidative stress (mg·L⁻¹ H₂O₂). The relationship is statistically significant (n = 20, R = 0.649, p<0.005). Panel B. Relationship between baseline uric acid values (mg·dL⁻¹) and oxidative stress (mg·L⁻¹ H₂O₂). The relationship is statistically significant (n = 22, R = 0.621, p<0.005). In both panels: full dots = patients with type 1 DM, open dots = healthy control subjects, dotted lines = 95% confidence limits.</p

Oxidative stress values throughout the 3-h exercises.

<p>Oxidative stress was significantly higher in patients (p<0.005), but remained essentially unchanged in both groups across the exercise (p = NS). Full dots = patients with type 1 DM, open dots = healthy control subjects.</p

Comparison between the estimated carbohydrates oxidation rate and the corresponding actually measured values.

<p>Relationship between the estimated carbohydrates oxidation rates over 30 min period of the exercise and corrected for the overall exercise duration, and the actually measured values. The relationship was statistically significant and close to the identity line (R = 0.877, p < 0.001, n = 54). Dashed lines are the 95% Confidence Limits. Dashed-dotted line is the identity line.</p

Blood glucose levels throughout the trials.

<p>Average glycemia (dots and thick line) throughout the trials is plotted against day-time; thin lines are the individual blood glucose levels at rest, before and throughout the 3-h exercise are also illustrated. Horizontal dashed lines: hypoglycemic and hyperglycemic thresholds.</p

Plasma insulin concentrations throughout the trials.

<p>Average laboratory measured plasma insulin concentrations (full dots and thick line) at rest, before and throughout the 3-h exercise is plotted against day-time; thin lines are the individual concentrations.</p

Demographic, clinical, and baseline biochemical parameters of the study subjects.

<p>Values are expressed as means ±SD. Parameters failing normal distribution (^§) are shown as median value and range (in brackets) and the Mann-Whitney U test was used to test their statistically significant differences.</p

Whole-body carbohydrates oxidation rates throughout the exercise.

<p>Average whole-body carbohydrates oxidation rates (full dots and thick line) are illustrated as a function of exercise duration. Thin lines are the individual oxidation rates.</p