In type 1 diabetes, some few studies have attempted to explore the impact of free-living self-reported physical activity (PA) sessions and the impact of accumulated spontaneous PA on hypoglycaemic risk, and less often on hyperglycaemic risk. However, no research has integrated in their analyses the confounding impact of sedentary time and/or of carbohydrate intake.
Fifty-eight children/adolescents living with type 1 diabetes have worn a continuous glucose monitoring (CGM) and an accelerometer for 7 days of free-living. During these 7 consecutive days, helped by an adult, children/adolescents reported scheduled and unscheduled PA sessions, specifying the exact PA and its time, duration and subjective intensity. For each meal/snack, the participants recorded the exact time, type, amount of food consumed and insulin dose. Linear mixed models or binary/multinomial logistic regressions with random effects were used to assess the effect of free-living PA on glycaemic metrics, controlling for carbohydrate intake, insulin administration and participants characteristics. Two sets of analyses were performed, as described in details in the paper: in the 1st analyses, we explored the effect of self-reported PA sessions on glycaemic metrics during the sessions, during two hours post-sessions and from two hours post-dinner to breakfast the next day. In the 2nd set of analyses, we explored the effect of cumulative PA and sedentary time (recorded with accelerometry) considered over different periods of the day, on concomitant or subsequent glycaemic (CGM) outcomes. The data made available on data.gouv correspond to all the data files used for these 1st and 2nd sets of analyses. Access to raw data of CGM and accelerometry would also be possible upon request to Elsa Heyman and Angéline Melin.
Data from 45 children/adolescents (21 females, 11‧7±3‧4years) were included. Accumulating moderate-to-vigorous PA (e>−0‧18, P<0‧05) or reducing sedentary time (OR=1‧01, P13‧9mmol.L-1 hyperglycaemia. Time spent >10‧0mmol.L-1 during self-reported PA sessions tended to decrease when children consumed less high-glycaemic index carbohydrates during the previous hour (e>+0‧40, P<0‧06) or performed other sessions before the current one (e<−11‧40, P<0‧05). Conversely, the latter conditions did not influence hypoglycaemic risk. The probability of spending time <3‧0mmol.L-1 during the night increased when children performed structured PA sessions of longer duration (OR=1‧02, P<0‧05) as well as when more vigorous-intensity PA was accumulated over the afternoon (OR=1‧07, P<0‧01).
The detailed results for all analyses are fully described in the paper.
In conclusion, increasing spontaneous active behaviours could help to reduce day-time level 2 hyperglycaemia. For children experiencing hyperglycaemia during exercise it could be advised to avoid excessive pre-exercise carbohydrate intake or multiply daily sessions number. However, as only characteristics of PA sessions (and not conditions under which they were undertaken) predicted risk of level 2 hypoglycaemia (nocturnal), simplified guidelines about hypoglycaemic risk could be developed.
