Abnormal Thermoregulation in Diabetic Autonomic Neuropathy

Hypothermia has been reported to be more common in diabetic people than in nondiabetic people, and we have investigated the possibility that autonomie neuropathy may be associated with disordered thermoregulation. After an overnight fast and maintenance of normoglycemia, 12 insulin-treated diabetic patients with and 11 without neuropathy and 12 nondiabetic control subjects, all <55 yr, were subjected to external cooling by perfusing water at 16°C through a liquid-conditioned coverall for ≤45 min. Patients with autonomie neuropathy had impaired vasoconstriction to cooling, particularly in the foot, calf, and forearm. Core temperature rose by 0.2°C in control subjects and by 0.15°C in patients with diabetes but no neuropathy. In contrast, group mean core temperature was unchanged in those with autonomie neuropathy and fell in 3 subjects (P < .001). Cooling caused shivering in 6 patients with diabetic autonomie neuropathy, but not in those with neuropathy or control subjects (P < .05). Baseline metabolic rates were similar in all three groups, but the increase after cooling was significantly greater among those who shivered (P < .05–.02). Thus, young diabetic patients with autonomie neuropathy have impaired thermoregulation to a relatively short period of external cooling, even during metabolic stability, which may predispose to hypothermia.