Objective: To examine the effect of type 1 diabetes on academic performance. Methods: Ethnically Saudi students with type 1 diabetes, and age, sex, ethnicity and socioeconomic status-matched nondiabetic control students were recruited from eight schools. Overall academic grades were recorded, based on the scores obtained in written examinations in English, mathematics, physics, chemistry, biology and humanities. Results: Students with type 1 diabetes (n ¼ 36) obtained significantly lower academic grades compared with their nondiabetic control classmates (n ¼ 36) (86.58 AE 1.48 vs 90.62 AE 1.36). Conclusions: Overall academic performance is significantly lower in students with type 1 diabetes compared with their nondiabetic classmates. This decline in academic performance may be explained by an association between diabetes and cognitive function.