OBJECTIVE: To assess whether nocturnal blood pressure dipping status in type 1 diabetes is correlated with specific sleep characteristics and differences in nocturnal glycemic profiles. RESEARCH DESIGN AND METHODS: Twenty type 1 diabetic adult patients underwent sleep studies with simultaneous 24-h ambulatory blood pressure monitoring and continuous nocturnal glucose monitoring. RESULTS: Altogether, 55% of patients exhibited blunted blood pressure dipping. They did not differ from the dipper group in age, BMI, or systolic (SBP) and diastolic (DBP) blood pressure. Total sleep period (TSP) was higher in the dipper group (497 +/- 30 vs. 407 +/- 44 min for dippers and nondippers, respectively, P < 0.001). TSP was correlated with SBP and DBP day-night differences (r = 0.44 and 0.49, respectively). Periods of nocturnal hypoglycemia (i.e., % of TSP with glycemia <70 mg/dl) were longer in the dipper group (8.1 +/- 10.7 vs. 0.1 +/- 0.4% for dippers and nondippers, respectively, P = 0.02). CONCLUSIONS: Dipping status in type 1 diabetes was associated with longer sleep duration and with hypoglycemia unawareness.