Acute Effects of Daily Life Spontaneous and Structured Physical Activity on Glycemia in Children with Type 1 Diabetes.

OBJECTIVES In type 1 diabetes, glycemia management is rendered complex through the confounding influence of spontaneous physical activity (PA), particularly frequent in children. We aim to understand the glycemic effects of self-reported PA and cumulative spontaneous PA in their everyday life, controlling for carbohydrate intake and insulin. METHODS In this 7-day observational study, 45 children/adolescents (21 females, 11‧7 ± 3‧4 years) wore a continuous glucose monitoring system and accelerometer, completing diaries about PA, diet, insulin. Types of PA included (i) self-reported PA and its characteristics (duration, subjective intensity) and conditions (previous sessions, timing and pre-exercise carbohydrate intake, insulin-on-board, glycemia), (ii) spontaneous cumulative PA (accelerometry) adjusted for sedentary time. Linear mixed models were used with results expressed as the estimated coefficient 'e'. In cases of skewed continuous dependent outcomes containing a preponderance of zero % values, random-intercept binary logistic regressions were used with results expressed as odds ratios (OR). RESULTS Accumulating moderate-to-vigorous PA during the late afternoon (e = -0‧32, P = 0‧039) was associated with decreased concomitant time spent >13‧9 mmol.L-1. Time spent >10‧0 mmol.L-1 during self-reported PA was lower when children consumed less high-glycemic-index carbohydrates the previous hour (e = +0‧49, P = 0‧034; albeit found only in one model out of two) or were physically active before the session (tendency: e = -11‧58, P < 0‧07). PA conditions were not significantly associated with hypoglycemia. Risk of spending some time < 3‧9 mmol.L-1 during sessions was higher in the case of longer PA duration (OR = 1‧02, P = 0‧008). Risk of nocturnal time < 3‧0 mmol.L-1 was greater when children performed longer duration structured PA (OR = 1‧02, P = 0‧054) or accumulated more afternoon vigorous-intensity PA (OR = 1‧06, P = 0‧04). CONCLUSIONS Increasing spontaneous active behavior during the late afternoon could help reduce day-time spent >13‧9 mmol.L-1. There is a possibility that hyperglycemia during exercise could be limited by multiplying daily PA sessions or avoiding excessive pre-exercise carbohydrate intake. However, as only sessions characteristics, especially duration, predicted time < 3‧9 mmol.L-1 during PA and < 3‧0 mmol.L-1 the following night, simplified guidelines (not considering PA conditions) on hypoglycemic risk could be developed.