Hormonal profile, blood sugar control and HLA patterns in long-term insulin dependent diabetes with and without vascular disease

The relationship of acute insulin sensitivity to the progression of vascular disease in long-term type 1 (insulin-dependent) diabetes mellitus

In 51 individuals with Type 1 (insulin-dependent) diabetes mellitus initially of more than 15 years' duration, the acute hypoglycaemic effect of intravenous insulin (0.11 IU/kg) was related to outcome over 18 years. This acute insulin sensitivity, or glucose assimilation index, was reproducible over the period of study. At 18-year follow-up, initial low glucose assimilation index (less than 0.082 mmol X l-1 X min-1 was significantly (p less than 0.01) associated with death from vascular disease. Low glucose assimilation index was similarly significantly (p less than 0.01) associated with progression of atherosclerotic disease, but not with microangiopathy alone. Hypertension (systolic blood pressure greater than 150 mmHg and/or diastolic blood pressure greater than 95 mmHg) was the only other parameter significantly (p less than 0.01) related to outcome, but this relationship was no longer significant once glucose assimilation index had been taken into account. A linear logistic analysis confirmed that acute insulin sensitivity was independently associated with outcome. Neither initial clinical control of diabetes nor glycosylated haemoglobin level in the 26 survivors was related to vascular prognosis.

Human insulin

Two methods of synthesis of human insulin have been developed to the stage of commercial production. One entails synthesis of human insulin by bacteria ("biosynthetic" human insulin) and one entails the conversion of pork insulin into human insulin by an amino acid substitution ("semisynthetic" human insulin). Both forms of human insulin have been shown to be safe, and to have similar efficacy and pharmacokinetics to purified pork insulin. Human insulin given by subcutaneous injection has been shown to elicit antibody formation in man, although the extent of this may be slightly less than in the case of purified pork insulin, and is certainly less than in the case of beef insulin and beef-pork combinations. The clinical significance of these differences in immunogenicity is doubtful. However there are rare defined situations, such as allergy to pork insulin and antibody-mediated insulin resistance where human insulin has been shown to have advantages over purified pork insulin. Bacterial synthesis of insulin provides an assured supply for the world's future needs, and it is conceivable that further technological refinement may make bacterial synthesis cheaper than extraction and purification of animal insulins. However, current evidence provides no basis for recommending human rather than purified animal insulin for the routine management of insulin dependent diabetes.

Effect of islet transplantation on the glomerular changes in streptozotocin-diabetic rats

Glomerular changes develop in rats with streptozotocin diabetes. The structure of these lesions (nodular and diffuse glomerulosclerosis, mesangial cell proliferation, basement membrane thickening, glomerular aneurysms, fibrinoid caps, glomerular adhesions) is described in the present paper and the effect of normalization of metabolism by islet transplantation on the glomerular changes is studied with histological, immunohistological and morphometric methods. Isogenous islets were transplanted into the portal vein of streptozotocin-diabetic rats after diabetes of 7 months' duration. The kidneys of normal, diabetic and transplanted animals of the same age were studied 2.5 months later. Studies of the kinetics of immunocomplexes in the mesangium were also performed. The renal changes (glomerulosclerosis, mesangial cell proliferation) were largely reversible after islet transplantation and the blood glucose level and glucose tolerance were normalized. In the diabetic animals the delayed uptake and elimination of immunocomplexes in the mesangium was normalized after the transplantation. It is possible, that the cause of the lesions is a functional disturbance of the mesangium induced by insulin deficiency and/or hyperglycaemia.

HLA patterns in Australian patients with insulin dependent diabetes mellitus (IDDM)

HLA antigens were determined in 169 Australian patients with insulin dependent diabetes mellitus (IDDM). HLA-B8 (47.9% v. 23.8%) and B15 (18.9% v. 8.2%) were significantly more frequent in the IDDM patients than in 1460 controls. The relative risks for developing IDDM in people carrying these antigens were 2.94 and 2.59 respectively. Carriers of the B8/B15 genotype had a relative risk of 5.48. These HLA associations in Australian IDDM patients are similar to those reported in other predominantly Caucasian populations.