Cardiorespiratory reflexes were studied during slow breathing and a Valsalva maneuver in 232 Type 1 (insulin-dependent) diabetic subjects. At 1 to 7 years follow-up, death occurred in 23.4% of 175 patients with abnormal reflexes and in 3.5% of 57 patients with normal reflexes. The mortality rates of diabetic subjects with abnormal reflexes were 17% at 2.5 years, 33% at 5 years and 40% at 7 years, significantly higher than for patients with normal reflexes (4.6%, 4.6% and 13.8%). Among patients with abnormal reflexes, patients with a functioning pancreas transplantation had better survival rates than patients with a failed transplantation, and in long-term follow-up better than patients without transplantation. A functioning transplantation prevented the progressive decline of cardiorespiratory reflex function that occurred over time in control patients.