The hyperinsulinaemic hypoglycaemias in infancy: a study of six cases

The aim of the present study was to evaluate various functional tests for the differentiation of hyperinsulinaemic hypoglycaemia. The pathophysiological and histological findings in six infants, aged 2-7 months, with persistent hyperinsulinaemic hypoglycaemia are described. Islet cell adenoma was found in four infants and pancreatic nesidioblastosis in two others. Circulating levels of blood glucose (BG), immunoreactive insulin and C-peptide immunoreactivity were measured under basal conditions and during both stimulation and suppression. The diagnosis of hyperinsulinaemia was made by estimation of the BG/serum insulin ratio, which was the most important diagnostic criterion of hyperinsulinism. Control subjects of comparable age showed a ratio of 8.3 +/- 4.4 (range 4.1-13.3), whereas the six patients had values between 0.3 and 5.1. At least four determinations with ratios lower than 2.6 were necessary for confirming the diagnosis. Preoperatively we performed oral glucose tolerance, diazoxide infusion, somatostatin infusion and C-peptide suppression tests. It is suggested that the various function tests, especially the suppression tests, do not differentiate hyperinsulinism caused by an adenoma from that caused by diffuse pancreatic nesidioblastosis.

Measurement of insulin in human sera using a new RIA kit. 1. Insulin determination in the absence of insulin antibodies--conventional assay and micro modification

A sensitive and versatile radioimmunoassay (RIA) for insulin was established using human insulin standard, a specific guinea pig anti-insulin antiserum and rabbit anti-guinea pig serum. Radioiodination was performed according to a modified chloramine T method. Tracer preparations were used for as long as 6 weeks after iodination. The standard curve ranges from 0.044 to 1.2 nmol/l. The intra-assay coefficient of variation (CV) was 3-5% and the inter-assay CV was 6-9% in the optimal range between 0.4 and 0.9 nmol/l. The average recovery of human insulin added to plasma or serum samples was 100.2 +/- 2.0% (n = 38) and 100.1 +/- 1.9% (n = 42), respectively. In addition to human insulin, porcine, canine, rabbit and bovine insulin can also be determined but not rat or mouse insulin. The cross-reactivity of the antiserum with porcine proinsulin was found to be 40% on the molar basis. The range of mean fasting plasma insulin concentrations in healthy subjects and under various pathological conditions were estimated.

Clinical and metabolic studies in children of diabetic-mothers

Children of diabetic mothers are a high-risk group. The perinatal mortality and the malformation frequency of the newborns as well as the psychosomatic, somatic and speech development during childhood until the age of 15 were statistically significantly influenced by quality of metabolic compensation, toxaemia and urinary tract infections during pregnancy. To evaluate the diabetogenic risk in children of diabetic mothers metabolic follow-up studies were performed. A statistically significant insulin-high-response without disturbed carbohydrate tolerance was seen in 25% after intravenous glucose infusion and in 28% after oral glucose load. 17% exhibited a paradoxical growth hormone reaction, while the intravenous glucose tolerance and the insulin secretion was in the normal range. Both symptoms could be early diabetic signs in children of diabetic mothers. The oGTT had pathological results in 18% and the glucose infusion test in 8%.

Determination of total insulin (TIRI) in plasma of insulin-treated diabetics and newborn infants of insulin-treated diabetic mothers

Plasma of insulin-treated diabetics and of newborn infants of insulin-treated diabetic mothers contains insulin antibodies which invalidates the radioimmunoassay of insulin. Therefore, the endogenous insulin antibody complex must be splitted at a pH lower than 5 and the total IRI (TIRI) is separated by ethanol extraction. It was investigated the recovery rate in dependence upon plasma volume used for extraction. By reduction of used plasma volume from 500 to 200 mul per extraction the recovery rate was increased from 65.1 +/- 8.4 to 88.3 +/- 4.2% (mean +/- SEM). The low plasma volume of 200 mul for TIRI extraction made it possible to determine TIRI during glucose loads of newborn infants. To eliminate different conditions of incubation for standard and unknown plasma samples the TIRI levels were computed by means of so-called "extracted" standard curve, obtained with extracted insulin from standard insulin dilution in insulin-free pooled human plasma. Using the described method a temporary regeneration of insulin secretion of a newly diagnosed juvenile diabetic after insulin treatment could be shown. In contrast to newborn infants of healthy mothers a biphasic/insulin release was found during the intravenous glucose loads in newborn infants of insulin-treated diabetic mothers.

Morphologie der Plazenta und neonatale Acidose bei mütterlichem Diabetes mellitus

Comparing the morphological findings of the placentas of acidotically born babies of diabetic mothers with non-acidotically born ones, we could find an extensive correlation of macroscopically detectable changes of the placentas (diminution of placental weight, insertio velamentosa of umbilical cord, aplasia of one umbilical artery) and histological findings (severity of diabetic maturation disturbances, size of villi) with the degree of the neonatal acidosis. With the severity of acidosis, the oedematosis of the placentas increases, too. When diabetic pregnancy is complicated by the EPH gestosis, a stronger fibrosis of the chorionic villi results. The oedematosis of the stroma recedes. The oedema of the placenta is in most cases correlated with the clinical appearance of the diabetic fetopathy (cushingoid newborn). According to our findings in cases complicated by the EPH gestosis, the oedematosis of the placenta and to a minor extent the cushingoid of the newborn are to be found more seldom.