Franciele Ramos Figueira

Aerobic and Combined Exercise Sessions Reduce Glucose Variability in Type 2 Diabetes: Crossover Randomized Trial

Purpose To evaluate the effects of aerobic (AER) or aerobic plus resistance exercise (COMB) sessions on glucose levels and glucose variability in patients with type 2 diabetes. Additionally, we assessed conventional and non-conventional methods to analyze glucose variability derived from multiple measurements performed with continuous glucose monitoring system (CGMS). Methods Fourteen patients with type 2 diabetes (56±2 years) wore a CGMS during 3 days. Participants randomly performed AER and COMB sessions, both in the morning (24 h after CGMS placement), and at least 7 days apart. Glucose variability was evaluated by glucose standard deviation, glucose variance, mean amplitude of glycemic excursions (MAGE), and glucose coefficient of variation (conventional methods) as well as by spectral and symbolic analysis (non-conventional methods). Results Baseline fasting glycemia was 139±05 mg/dL and HbA1c 7.9±0.7%. Glucose levels decreased immediately after AER and COMB protocols by ∼16%, which was sustained for approximately 3 hours. Comparing the two exercise modalities, responses over a 24-h period after the sessions were similar for glucose levels, glucose variance and glucose coefficient of variation. In the symbolic analysis, increases in 0 V pattern (COMB, 67.0±7.1 vs. 76.0±6.3, P = 0.003) and decreases in 1 V pattern (COMB, 29.1±5.3 vs. 21.5±5.1, P = 0.004) were observed only after the COMB session. Conclusions Both AER and COMB exercise modalities reduce glucose levels similarly for a short period of time. The use of non-conventional analysis indicates reduction of glucose variability after a single session of combined exercises. Trial Registration Aerobic training, aerobic-resistance training and glucose profile (CGMS) in type 2 diabetes (CGMS exercise). ClinicalTrials.gov ID: NCT00887094.

Accuracy of continuous glucose monitoring system during exercise in type 2 diabetes

The concordance of continuous glucose monitoring system (CGMS) and finger-stick blood glucose (FSBG) was assessed in patients with type 2 diabetes during daily activities and two different exercise sessions. Agreement between FSBG and CGMS becomes weaker during exercise, but more than 90% of the CGMS readings are within acceptable range.

Exercise on Progenitor Cells in Healthy Subjects and Patients with Type 1 Diabetes.

PURPOSE To evaluate the acute effect of aerobic exercise (AE) and resistance exercise (RE) on the release of endothelial progenitor cell (EPCs, CD34+/KDR+/CD45 dim) and vascular function in type 1 diabetes (T1DM). METHODS Fourteen men with T1DM and 5 nondiabetic controls were randomly assigned to 40-min AE (60% VO 2peak) and RE sessions (60% 1-RM). The study had a crossover design, and interventions were 1 wk apart. Venous occlusion plethysmography (blood flow, reactive hyperemia, and vascular resistance) and blood collection (EPC levels, flow cytometry) were done immediately before and after exercise sessions. RESULTS Patients were 30.3 ± 1.6 yr-old, HbA1c 7.7% ± 0.2%; controls were 26.8 ± 2.3 yr-old. Groups did not differ in EPC levels at baseline or in relation to exercise. Over time, exercise did not induce changes in patients with T1DM, whereas, in controls, EPCs were decreased after AE (-10.7%, P = 0.017) and increased after RE (+12.2%, P = 0.004). Compared with baseline, blood flow increased and vascular resistance decreased after RE in both groups. Reactive hyperemia was increased 10 min after AE and RE sessions in patients with T1DM (36.5% and 42.0%, respectively) and in controls (35.4% and 74.3%), but no group differences were observed between groups in response to exercise. CONCLUSIONS Despite the increased vascular reactivity in both groups after both exercise sessions, EPCs were only influenced by exercise in controls. The unchanged number of EPCs in T1DM after exercise sessions might indicate a blunted endothelium regenerating capacity, revealing an early deterioration of the functional arterial characteristics not disclosed by only evaluating vascular functional variables.

Effect of Acute Inspiratory Muscle Exercise on Blood Flow of Resting and Exercising Limbs and Glucose Levels in Type 2 Diabetes

To evaluate the effects of inspiratory loading on blood flow of resting and exercising limbs in patients with diabetic autonomic neuropathy. Ten diabetic patients without cardiovascular autonomic neuropathy (DM), 10 patients with cardiovascular autonomic neuropathy (DM-CAN) and 10 healthy controls (C) were randomly assigned to inspiratory muscle load of 60% or 2% of maximal inspiratory pressure (PImax) for approximately 5 min, while resting calf blood flow (CBF) and exercising forearm blood flow (FBF) were measured. Reactive hyperemia was also evaluated. From the 20 diabetic patients initially allocated, 6 wore a continuous glucose monitoring system to evaluate the glucose levels during these two sessions (2%, placebo or 60%, inspiratory muscle metaboreflex). Mean age was 58 ± 8 years, and mean HbA1c, 7.8% (62 mmol/mol) (DM and DM-CAN). A PImax of 60% caused reduction of CBF in DM-CAN and DM (P<0.001), but not in C, whereas calf vascular resistance (CVR) increased in DM-CAN and DM (P<0.001), but not in C. The increase in FBF during forearm exercise was blunted during 60% of PImax in DM-CAN and DM, and augmented in C (P<0.001). Glucose levels decreased by 40 ± 18.8% (P<0.001) at 60%, but not at 2%, of PImax. A negative correlation was observed between reactive hyperemia and changes in CVR (Beta coefficient = -0.44, P = 0.034). Inspiratory muscle loading caused an exacerbation of the inspiratory muscle metaboreflex in patients with diabetes, regardless of the presence of neuropathy, but influenced by endothelial dysfunction. High-intensity exercise that recruits the diaphragm can abruptly reduce glucose levels.

Inspiratory muscle loading: a new approach for lowering glucose levels and glucose variability in patients with Type 2 diabetes

Glucose variability reflects glycaemic excursions that ultimately contribute to increased levels of protein glycation and oxidative stress [1]; therefore, analysis of glucose variability may be promising as a target for intervention to reduce organ damage in patients with Type 2 diabetes. Physical exercise reduces glycaemia and glucose variability in diabetes [2], but the effects of diaphragm muscle contractions induced by inspiratory loading are still unknown. Accordingly, we aimed to compare glucose levels and glucose variability after aerobic, combined exercise and inspiratory muscle-loading exercise in patients with Type 2 diabetes. Fourteen patients with Type 2 diabetes, treated with metformin participated in a crossover trial from two other studies previously approved by the institutional review board; all participants gave their written informed consent. The participants underwent two conventional exercise protocols (aerobic or combined exercise) in a randomized order. For the aerobic session, participants exercised on a cycle ergometer (Embreex 360, Brusque, Brazil) for 40 min at 70% of peak heart rate. In the combined session, the same aerobic protocol was performed for 20 min, complemented by four resistance exercises (leg press, leg extension, bench press and biceps curl), with three sets of 12 repetitions at 65% of one repetition maximum (1 RM). Six of 14 participants who performed aerobic and combined exercise were also randomly assigned to two sessions of inspiratory muscle-loading exercise [high resistance, 60% of maximum inspiratory mouth pressure (PImax) or low resistance, 2% of PImax]. The inspiratory muscle-loading exercise at 60% of PImax protocol was designed to cause fatigue of the diaphragm at intensities > 80% of maximal oxygen consumption (VO2max) [3]. The participants breathed through a two-way valve (Hans Rudolph, 2600 series; Shawnee, KS, USA) with high resistance of inspiratory muscle at 60% of PImax, connected to a POWERbreathe inspiratory muscle trainer (HaB International, Southam, UK) or to a threshold inspiratory muscle trainer (DHD, Chicago, IL, USA) for low resistance of inspiratory muscle at 2% of PImax. In both protocols, the baseline data were collected during 5 min of spontaneous breathing. Thereafter, distinct inspiratory and expiratory audio tones were used so that participants could maintain a breathing frequency of 15 breaths per min and a duty cycle of 0.7. Inspiratory pressure was continuously recorded and displayed on a computer screen and a 10-point Borg scale was used to assess inspiratory effort at task failure. Inability to maintain breathing was defined as a reduction of PImax to < 80% of the prescription during three consecutive breaths. As the low resistance experiments do not induce task failure (inspiratory muscle-loading exercise, 2% of PImax), measurements were recorded for 5 min. Thus, in the high resistance session at 60% of PImax (inspiratory muscle-loading exercise), the participants performed breath control/3 min; 60% loading/ ~ 5 min and, in the low resistance session at 2% of PImax (inspiratory muscle-loading exercise), they performed breath control/3 min; 2% loading/ 5 min. For all exercise protocols, participants wore a continuous glucose monitoring system. The four experimental sessions took place 7 days apart. Glucose measurements were obtained every 5 min; these profiles were obtained for 30 min before, during and for 30 min after exercise sessions. Glucose standard deviation, glucose variance and glucose coefficient of variation were calculated for each series, before and after sessions. Two-way ANOVA and multiple comparison tests (Student–Newman–Keuls) were performed. Statistical significance was accepted at a P value ≤ 0.05. Participants were aged 56 7 years, had a BMI 30 4 kg.m 2 and HbA1c levels 61 5 mmol/mol (7.9 0.6%), characteristics that were similar between those who performed aerobic, combined and inspiratory muscle loading exercise (n = 6) and those who performed only aerobic and combined exercise (n = 8). Figure 1a shows glucose levels determined by the continuous glucose monitoring system, whichwere reduced after aerobic (25%), combined (11%) and inspiratory muscle-loading exercise at 60% of PImax (24%). Glucose variability evaluated by glucose standard deviation reduced after exercise aerobic and inspiratory muscle-loading exercise at 60% of PImax sessions, but not by combined or inspiratory muscle-loading exercise at 2% of PImax (Fig. 1b). Similar findings were obtained for glucose variability evaluated by glucose variance (Fig. 1c). Glucose coefficient of variation decreased only after inspiratory muscle-loading exercise at 60% of PImax session (Fig. 1d). The low resistance of inspiratory muscle-loading exercise at 2% of PImax did not cause any change in glucose levels. In the present paper, we report for the first time that high resistance of inspiratory muscle exercise at 60% of PImax reduces glucose levels immediately after an acute session, similarly to aerobic and combined sessions. Moreover, aerobic and inspiratory muscle exercise at 60% of PImax promote similar reductions in glucose variability, which were not observed after a single combined session or inspiratory

A single session of aerobic or resistance exercise modifies the endothelial progenitor cell levels in healthy subjects, but not in individuals with type 1 diabetes

Materials and methods We conducted a crossover randomized clinical trial, in which 14 men with T1D and 5 healthy controls were randomly assigned to a 40-min AE session (60% VO2peak) and a 40-min RE session (60% maximal load), 1 week apart. Venous blood was collected 10 min pre and postexercise sessions to evaluate circulating EPCs (percentage of CD34+/KDR+/CD45dim of 200.000 mononuclear cells gated and analyzed by flow cytometry). Forearm BF and RH were evaluated by venous occlusion plethysmography before and after the sessions. Generalized Estimation Equation adjusted for baseline values was used. Results Patients were 30.3±1.6 yrs-old, HbA1c 7.7±0.2%; controls were 26.8±2.3 yrs-old. Exercise did not change EPCs in T1D [AE (-5.075±0.250 vs. -5.303±0.250, P=0.102); RE (-5.217±0.250 vs. -5.056±0.250, P=0.310)]; EPCs decreased after AE (-4.383±0.353 vs. 4.854±0.353, P=0.017) and increased after RE (-5.270±0.353 vs. -4.629±0.353, P=0.004) in controls. Blood flow increased after RE in patients with diabetes (28.7±11.4%, P=0.009) and controls (41.7±18.5%, P=0.024). Reactive hyperemia was increased after AE (36.5±7.3%, P<0.001), and RE (42.0±10.0%, P<0.001) in patients with diabetes and controls (AE: 35.4±11.0%, P=0.001; RE: 74.3±33.0%, P=0.005).