Pancreatic polypeptide secretion after insulin infusion and protein meal in juvenile type 1 diabetic subjects

An impaired pancreatic polypeptide response (PP) after hypoglycemia has been described in type I diabetic patients with overt autonomic neuropathy. Some authors have suggested that PP release might be useful as sensitive indicator of autonomic neuropathy. The meal test is safer and simpler than the insulin infusion test as PP stimulus. The aim of this study was to compare PP response to insulin infusion and protein meal test and to correlate these responses to the presence of measurable neuropathic disturbances. We thus studied 13 IDDM children and adolescents and 6 normal children. In diabetics the PP response to both tests was not different from that of the control subjects, but PP response to insulin infusion was inversely correlated to the duration of illness and was significantly lower in subjects with pathological heart rate response when compared to the control group. PP responses to the two stimuli were not correlated. We suggest that reduced PP response to hypoglycemia is an early sign of autonomic neuropathy as well as impairment of beat-to-beat variation when impaired PP response to meal test is still not evident.