PHYSICAL ACTIVITY AND NUTRIENT INTAKE IN YOUTH WITH TYPE 1 DIABETES

Objectives. Although physical activity (PA) is fundamental to T1D care, its impact on glycemia remain variable. This project was developped in three phases: i) We investigated the average and amount of PA in youth with T1D and we investigated possible associations with metabolic outcomes; ii) We examined associations between exercise energy expenditure (EE) and glycemia assessed by continous glucose monitoring (CGM) and between EE and dietary intakes in youth with T1D; iii) we tested the performance of the new isCGM system during high intensity interval PA, as a possible tool to and support exercise in youth with T1D. Study A. Methods. Youth reported frequency, amount, and type of PA in a typical week; moderate and vigorous PA (4 and 8 METs, respectively) were combined. Youth were compared by frequency of PA (0-5 vs 6-7 days/week (d/wk)). Blood was assayed for glycemic control (A1c; 1,5-anhydroglucitol (1,5-AG)) and lipids. Body composition was assessed by DXA. Results. Youth (49% male) were 12.8±2.6 y/o, with T1D for 5.9±3.1 yrs, A1c 8.1±1.0%, 70% pump Rx, BG monitoring 5.7±2.4 X/d. Median PA was 9.5 hours/wk (range 0-42); 6% had PA 0 d/wk, 17% 1-3 d/wk, 29% 4-5 d/wk, 49% 6-7 d/wk. Youth with PA 6-7 d/wk were more likely to be male (62% vs 38%; p=.002), younger (12.3±2.5 vs 13.4±2.5 y/o; p=.01), with shorter T1D duration (4.8±2.6 vs 7.0±3.2 yrs; p< .0001) than youth with PA 0-5 d/wk. PA 6-7 d/wk associates with lower insulin resistance and glycemic excursions (1,5-AG), better body composition and lipid profile. No variables were significantly correlated with total hr/wk of PA when adjusting for d/wk of PA. Conclusions. These data in T1D youth suggest that PA frequency favorably impacts insulin resistance, body composition, lipids, and possibly glycemic excursions (1,5-AG). Further research is needed to determine a means to improve A1c with PA. Study B. Methods. Youth (N=125, 49% male) with T1D wore masked CGM for 3 days; youth and/or parents documented youth physical activity (PA) by recording type, duration, and intensity of exercise. Using the Compendium of Energy Expenditure for youth (Ridley et al.), we assigned a MET value to each PA and calculated 24-hour adjusted EE (kcal/day). CGM data were categorized as % hypo (<70 mg/dL), % in range (70-180 mg/dL), and % hyperglycemia (>180 mg/dL). No differeneces were found in dietary intakes among the three EE groups. Results. Mean age was 12.9±2.6 years, T1D duration 5.9±3.2 years; 21% were overweight and 11% obese. Most (71%) were pump treated; youth received 0.9±0.3 U/kg/day and had a mean A1c of 8.1±1.0%. Median EE was 340 kcal/day (IQR 161-666), Youth were compared according to tertiles of EE. While tertiles did not differ by age, sex, or pump therapy, youth in the lowest tertile had the longest T1D duration and highest A1c. EE was significantly and inversely related to both % body fat by DXA and CGM% hyperglycemia and directly related to CGM % in range. Conclusion: PA can favorably impact glycemia assessed by CGM and body composition by DXA. Study C. Methods. Seventeen youth (53% male), aged 13.73.8 years, with T1D for 5.43.8 years, HbA1c 7.41.0% (5711 mmol/mol), were enrolled. Paired isCGM, plasma (PG) and capillary (CG) glucose values (total of 136) were collected during an interval exercise (45 min at 55% VO2max load with 20 seconds sprints at 80% VO2max every 10 minutes). Paired isCGM and CG (total of 832) were collected during free-living condition. Results. During exercise, isCGM absolute relative difference (ARDs) means/medians were 12.5/9.4% versus PG and 15.4/10.8% versus CG. During rest, ARDs means/medians were 16.6/12.0%. The Consensus Error Grid analysis showed 98.4% of readings during exercise and 97.24% during rest in zones A+B. Percentage of readings meeting the ISO criteria for CG levels <5.55 mmol/L was 62.5% during exercise, 53.4% during rest; for CG levels5.55 mmol/L was 64.0% during exercise, 60.4% during rest. Conclusions. isCGM demonstrated similar clinical safety and performance during exercise and in everyday life; further studies are needed to confirm its accuracy during exercise.