Opiate receptors and the metabolic response to intravenous glucose.

The role of opiate receptors in the metabolic response to an intravenous glucose load was determined in eight non-diabetic subjects (four of whom showed a positive chlorpropamide alcohol flush response and four who did not). Subjects were studied in a double blind randomised fashion receiving either a saline control or the specific opiate receptor antagonist, naloxone (0.4 mg/min), as an infusion for 5 minutes before and 20 minutes after an intravenous bolus of glucose (0.5 g/kg body weight). Naloxone decreased the early plasma glucose peak in all subjects by increasing the distribution volume but did not alter the fractional glucose clearance. Insulin and glucagon responses to glucose were not altered by naloxone. Naloxone delayed the normal post-glucose rise in the levels of the gluconeogenic precursors alanine, lactate, pyruvate and glycerol suggesting a delay in the usual inhibition in gluconeogenesis following a glucose load. There was no difference in the metabolic response between those subjects who were liable to chlorpropamide alcohol flushing and those who were not either with or without naloxone. We conclude that opiate receptors may influence distribution volume and gluconeogenesis but do not play a major role in either insulin or glucagon secretion or in glucose disposal following an intravenous glucose load.

Neutrophil and lymphocyte function in patients with diabetes mellitus.

Neutrophil granulocyte chemotaxis and intraneutrophilic and plasma levels of lysozyme as well as the number of T and B lymphocytes and lymphocyte transformation in vitro on stimulation with mitogens and microbial antigens were studied in four groups of patients with diabetes mellitus (DM). Twelve patients with insulin-dependent diabetes mellitus (IDDM) and ketoacidosis and 4 patients with non-insulin-dependent diabetes mellitus were studied at the time of diagnosis and before and after start of treatment. Ten patients with IDDM of less than 10 years' duration which had been difficult to regulate well and 10 patients with IDDM well regulated for more than 20 years were studied at their regular outpatient visits. Apart from a slight increase in plasma lysozyme in group 1 from the first to the second examination, we found no differences between diabetics and healthy control persons. It is concluded that if patients with DM are more susceptible to infections, it is probably caused by elements of neutrophil or lymphocyte function not examined in this study or by factors unrelated to immunity.

Stimulatory effect of serum from diabetic patients on insulin release from mouse pancreatic islets maintained in tissue culture.

Islets of Langerhans from NMRI-mice were kept for one week in tissue culture in medium supplemented with human serum obtained from either normal healthy subjects or newly diagnosed juvenile diabetic patients before insulin treatment. Islets cultured in diabetic serum released more insulin than islets cultured in normal serum, whether tissue culture medium 199 with 5.5-8.3 mmol/l glucose and 10% serum, or culture medium RPMI 1640 with 11 mmol/l glucose and 0.5% serum were used. Islets kept for one week in culture with diabetic serum did not show any decrease in DNA content or glucose induced insulin secretion and biosynthesis. It is concluded that serum from newly diagnosed insulin-dependent diabetic patients stimulates insulin release from isolated mouse islets kept in tissue culture. The underlying mechanism is unknown.

Persistent insulin secretion, assessed by plasma C-peptide estimation in long-term juvenile diabetics with a low insulin requirement.

In order to investigate whether patients with long-standing juvenile diabetes mellitus (onset of diabetes before the age of 30) and a low daily insulin requirement (less than 0.50 units/kg body weight) still have functioning B-cells, plasma C-peptide was determined after stimulation (OGTT and glucagon/tolbutamide) in 64 patients with diabetes of more than 18 years' duration (mean 31 years). Measurable endogenous insulin production was found in 24% of the patients. The prevalence of severe retinopathy was lower in the secretors than in the non-secretor group. There was no difference in insulin antibody concentration between the two groups. Furthermore, the insulin requirement in the secretor group was relatively constant during the course of diabetes. Metabolic control was similar in both groups. It is concluded that a persisting but low activity of endogenous insulin production can be found in many long-term juvenile diabetics with a low insulin requirement, while others without any residual beta-cell function develop a low insulin requirement for unknown reasons.

Insulin release, insulin content, and glucose utilization in isolated mouse islets maintained in tissue culture.

To elucidate the remission phase in juvenile diabetics the insulin release, insulin content, and glucose utilization were measured in isolated Langerhans' islets from mice maintained for 6 days in a tissue culture at a glucose concentration of 278 mmol, followed by a culture period of 4 days at 6.1 mmol glucose. These experiments revealed that the ability of the islets to store and secrete insulin during glucose stimulation decreased considerably during incubation at high concentrations of glucose. When the glucose concentration in the incubation medium was reduced, these properties could be re-established. Basal as well as glucose-stimulated glucose utilization increased greatly during incubation at high glucose concentrations. However, it was not possible to normalize the glucose utilization during 4 days' incubation at 6.1 mmol glucose. The results indicate that unphysiologically high concentrations of glucose may induce long-lasting changes in the function of Langerhans' islets.