['Sleep restriction has been associated with deteriorated insulin sensitivity. The effects of short sleep duration have been explored little in patients with type 1 diabetes. This study addresses the question of whether sleep curtailment affects HbA1c levels in patients with type 1 diabetes.', 'Seventy-nine adult patients with type 1 diabetes (median age 40 years [IQR 23-49]; 47% men) were recruited to wear a wrist actimetry sensor during 3 consecutive days to assess mean sleep duration during normal daily life. A subsample of 37 patients also performed 24-h ambulatory blood pressure monitoring (ABPM). Medical history, sleep questionnaires, and diabetes-related quality of life (DQOL) were assessed.', 'Patients having shorter sleep duration--less than 6.5 h (n=21)--had higher levels of HbA1c (P=0.01) than patients with longer sleep duration, above 6.5 h (n=58). In a multivariable regression model including shorter versus longer sleep duration, diabetes duration, DQOL score, and daily activity, sleep duration was the only variable independently associated with HbA1c (R2=10%). In patients who performed 24-h ABPM, patients with a nondipping pattern of blood pressure exhibited shorter sleep duration than patients with a dipping pattern of blood pressure.'] Is short sleep duration measured by wrist actimetry associated with deteriorated glycemic control in type 1 diabetes?