BackgroundWe explore the association between hypoglycaemia fear (FH) and glycaemia during and after exercise sessions in a large sample of physically active youth with type 1 diabetes (T1D).MethodsWe used data from the Type 1 Diabetes Exercise Initiative Paediatric (T1DEXIP) Study. Youth self‐reported on FH using the Hypoglycaemia Fear Survey‐Child (HFS‐C). They used a smart phone application to self‐report food intake and insulin dosing (multiple daily injection only). We collected pump and continuous glucose monitoring data directly from the device.ResultsOur sample included n = 251 youth (mean age: 14 ± 2 years, 55% closed loop pump; 42% women). Youth reporting higher HFS‐C Total and Helplessness/Worry scores (HFS‐C subscale) had slightly fewer competitive and fewer high intensity exercise events compared to youth with lower HFS‐C Total and Helplessness/Worry scores. Youth reporting the highest Maintain High Blood Glucose scores (HFS‐C subscale) had the lowest percent glucose time in range, higher mean glucose levels, and higher percent time above range during exercise. Youth reporting the highest Maintain High Blood Glucose scores also tended to have higher mean glucose levels post‐exercise and a smaller drop in glucose during exercise.ConclusionFH relates to glycaemia during and after exercise in adolescents with T1D and may signal an inclination for some youth to engage in avoidance behaviours to reduce their vulnerability to exercise‐induced hypoglycaemia.