Data collected as routine clinic procedure and will be used to assess changes in HbA1c and BMI from baseline to follow-up.

Total of all reporting groups

Body mass index (calculated from height (cm) and weight (kg) measures from clinic records)

Children rate a range of activities on a three-point scale representing how much of that activity they did (none, a little, a lot) at three time points in the previous 24 hours; today before school (22 items), yesterday after school (22 items), and yesterday during school (11 items). Scores are summed to form a total score for physical activities (possible range 41-123). Higher values represent higher physical activity (i.e., better outcome).

CSAPPA = Children's Self-Perceptions of Adequacy in and Predilection for Physical Activity The CSAPPA scale measures generalised self-efficacy and attitudes towards participation in physical activity. The 19-item CSAPPA scale measures children's perceived adequacy, predilection and enjoyment towards physical activity. Each item is scored from 1 to 4 and total CSAPPA scores range between 19 - 76 with higher scores indicative of greater self-efficacy (i.e., better outcome).

Total score calculated as the sum of all sub-scales (CSAPPA adequacy + CSAPPA predilection + CSAPPA enjoyment)

Perceived adequacy (7 items) refers to the perception of one's ability to achieve some acceptable standard of success, that standard being influenced by the self, parents, peers, teachers and society's expectations. Range of scores 7 - 28, with higher scores indicating higher perceived adequacy (i.e., better outcome).

Predilection (9 items) refers to the preference for being active over being sedentary when given the choice. Range of scores 9 - 36 with higher scores indicating higher predilection towards physical activity (i.e., better outcome).

Enjoyment (3 items) refers to enjoyment of Physical Education (P.E.) class. Range of scores 2 - 12 with higher scores indicating greater enjoyment of P.E (i.e., better outcome).

PHFS = Parents' Hypoglycaemia Fear Survey The 26-item PHFS measured parents' fear of hypoglycaemia and the negative consequences of these episodes, as well as behaviours used to avoid hypoglycaemia and its negative consequences. The measure comprises a behaviour subscale and a worry subscale.

Total score calculated as the sum of both sub-scales (PHFS Behaviour + PHFS Worry).

Scores range from 0-104. Higher score indicates greater fear of hypoglycaemia (i.e., worse outcome).

11 items on the PHFS-behaviour subscale assess the behaviours that parents may engage in as a result of fear of hypoglycaemia (e.g., 'avoid having my child being alone when his/her sugar is likely to be low'). Items refer to diabetes management behaviours parents may perform to reduce the chance of hypoglycaemia, the tendency to keep blood glucose levels high to avoid hypoglycaemia and behaviours aimed at avoiding the negative consequences of hypoglycaemia.

Scores range from 0-44. Higher score indicates more hypoglycaemia avoidance behaviours (i.e., worse outcome).

15 items on the PHFS-worry subscale address specific worries that parents may have in relation to various aspects of hypoglycaemia (e.g., 'child not having food, fruit or juice with him/her'). Items on the worry subscale assess worry about hypoglycaemia occurring when the child is alone or when there is no food or drink available, worry about the child having an accident or physical injury, and worry about the child being unable to function normally. Scores on the worry subscale range from 0-60. Higher score indicates greater worry (i.e., worse outcome).

Glycaemic control measured in mmol/mol. UK recommended level for good diabetes control is currently <58mmol/mol for children.

Higher score indicates worse outcome. Lower score (<58mmol/mol) indicates better outcome.

Number of participants completing outcome measures at T3

Attendance at physical activity sessions and completion of activity diary Intervention group only as the Control group were not exposed to any intervention.

Data collected as routine clinic procedure and will be used to assess changes in HbA1c and BMI from baseline to follow-up.

Number of participants experiencing and/or reporting adverse events.

Treatment as usual: children asked to continue normal daily activity as usual.