SummaryIn 58 consecutive pregnancies in insulin-dependent diabetic women, glycosylated haemoglobin levels were abnormally high in 78% at the time of booking for antenatal care.Spontaneous abortion was the outcome in 15 pregnancies, 10 occurring before the 15th week of gestation. Glycosylated haemoglobin levels were significantly higher in those women who aborted spontaneously than in women who delivered successfully (128 ±+ 1.8% v. 112 ±+ 2.3%, mean ± s.d.). These results emphasise the inadequacy of diabetic control in the first trimester and lend further support to the importance of good control at this critical time in insulin-dependent diabetes.
The paracrine role of glucagon i n stimulating insulin secretion was investigated by neutralisi n g A-cell glucagon w i t h an anti-glucagon immunoglobulin (Ig) fraction prepared by ammonium sulphate precipitation. I t s specificity was checked by cross-reactivity studies w i t h g u t peptides and insulin. 0.5 ml of the rabbit anti glucagon Ig was injected into rats ( i v ) , w h i l s t control rats were administered 0.5 ml of normal rabbit serum (NRS) Ig fraction. i s l e t s were isolated from the r a t s a f t e r 20 min using a collagenase technique (2 mg/ml). Between 5-10 i s l e t s were placed i n each experimental tube and incubated a t 37OC i n Krebsbicarbonate buffer containing 0.2% bovine serum albumin. Time course studies of insulin release were carried out. In the control i s l e t s there was a biphasic i n s u l i n response t o arginine hydro chloride (4mM). T h i s insulinotrophic effect was abolished i n i s l e t s from the anti-glucagon pretreated r a t s (n=6;p<0.001). A further series of experiments were conducted i n which i s l e t s from normal r a t s were incubated i n the presence o r absence of anti-glucagon Ig fraction. In the presence of Ig from NRS (1:20), arginine hydrochloride (4mM) stimulated i n s u l i n secretion (50.0f2.0 ng/mg islet protein) compared w i t h cont r o l s (17.2?1.1 ng/mg islet protein). This insulinotropic effect was abolished by addition of anti-glucagon Ig t o the medium (17.8k0.4 ng/mg islet; n=5;p<0.001). D-glucose (20M) i n the medium stimulated i n s u l i n secretion both from i s l e t s incubated w i t h Ig from NRS (37.8?2.2 ng/mg islet) o r anti-glucagon Ig (38.8f2.6 ng/mg islet).The results suggest that different mechanisms are involved i n insulin release by glucose and by arginine and provide further evidence f o r the paracrine effect of A-cell glucagon on i n s u l i n secretion.
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