Beta-cell cytoadherent lymphocytes in some subjects at risk for type 1 (insulin-dependent) diabetes: progression to diabetes within 2 years

[Detection of subjects at risk of type 1 diabetes. GOFEDI. Groupe Ouest-France pour l'Etude du Diabète Insulino-dépendant]

The so-called type 1 (insulin-dependent) diabetes is an autoimmune disease occurring in genetically predisposed subjects. The clinical onset of the disease is preceded by a subclinical period during which insulin-producing cells are progressively destroyed by immunological effectors. This prediabetic phase can be detected by the presence of autoantibodies directed against islet cells and sometimes associated with anti-insulin antibodies in children, and later on by the disappearance of the early insulin secretion peak in response to intravenous glucose. It is at this prediabetic phase that immunomodulators specific to the antipancreas process and devoid of side-effects will be used, when available, and that an early insulin therapy will be instituted.

Acute insulin response to intravenous glucose, glucagon and arginine in some subjects at risk for type 1 (insulin-dependent) diabetes mellitus

The relationships between first-phase insulin secretion to i.v. glucagon and i.v. arginine were studied in 19 healthy adult volunteers (Group I) and in 21 subjects at risk for Type 1 (insulin-dependent) diabetes mellitus with either a "normal" (n = 11; Group IIa) or a "low" insulin response to i.v. glucose (n = 10; Group IIb). Groups I and IIa displayed similar insulin responses to the three secretagogues. In contrast, Group IIb demonstrated lower insulin responses to both glucagon and arginine than control subjects (p less than 0.007 and p less than 0.04 respectively) or than "normo-responders" to glucose (p less than 0.007 and p less than 0.04 respectively). In Group IIb however, arginine-stimulated insulin release was increased compared to the response to glucose (p less than 0.006), while glucagon and glucose led to non-statistically different responses. Five "low-responders" developed Type 1 diabetes. As a group, they displayed lower responses to glucagon and to arginine than subjects who up to now have not developed the disease (p less than 0.05 and p less than 0.0003 respectively). In the subjects who progressed to diabetes, the responses to glucose and glucagon were similarly blunted. In the "low-responders" who have not developed the disease, no statistical difference could be detected between mean responses to glucagon and glucose, but four out of these five subjects had a glucagon-stimulated response within the control range and higher than their corresponding response to glucose. Arginine led to a higher stimulation than glucose, in subgroups that either progressed to diabetes (p less than 0.006) or did not (p less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin attenuates low-dose streptozotocin-induced immune diabetes in mice and inhibits the beta-cell binding of T-splenocytes in vitro

Five low doses (40 mg.kg-1.day-1) of streptozotocin were given to CD-1 mice to induce "immune" diabetes with insulitis. T-splenocytes (L3T4+ and Lyt2+) from streptozotocin-treated mice were previously reported to display in vitro an increased binding for Beta cells, preceding the onset of hyperglycaemia and of insulitis. Since heparin inhibits lymphocyte traffic, displays anti-adhesive properties, and attenuates some cell-mediated immune diseases, we have investigated the effects of heparin and N-desulphated heparin: 1) in vivo on low-dose streptozotocin-induced diabetes and insulitis, and 2) in vitro on the increased binding of T-splenocytes from streptozotocin-treated mice to rat insulinoma (RINm5F) cells. Daily subcutaneous low doses (5 micrograms or 10 micrograms) of heparin induced a delay in onset and a reduction of the severity of hyperglycaemia and insulitis (p less than 0.01), and reduced the incidence of diabetes (p less than 0.01). Similar effects were obtained with 5 micrograms daily doses of N-desulphated heparin devoid of anticoagulant activity. In contrast, lower (1 microgram) or higher (200 micrograms) doses of heparin were ineffective. Heparin (10 micrograms) did not modify the "toxic" diabetes induced by a single high dose (200 mg/kg) of streptozotocin. On the other hand, heparin dose-dependently (0.1 microgram/ml to 500.0 micrograms/ml) inhibited the increased binding of splenocytes from streptozotocin-injected mice to RIN cells as compared to splenocytes from control mice. This in vitro anti-adhesive effect was detected when either splenocytes or RIN cells were pretreated with heparin before their co-incubation, and was also obtained with N-desulphated heparin.(ABSTRACT TRUNCATED AT 250 WORDS)