Niichternserum-Gesamt-IRI zwischen 6 und 4374 ?E/ml (Mittelwert 392 ~xE/ml). Im Laura der Insulinbehandlung stieg das Gesamt-IRI yon Normalwerten, die w/~hrend dot ersten 2 Monate registriert wurden, ant ein h6heres Niveau an, das sich naeh etwa 5 Monarch Behandlungsdauer stabilisierte. Der Anstieg des It~I erfolgte gleichzoitig mit der Bildung yon Antik6rpern. Bei insulinresistenten Patienten ergaben sich sehr hohe IRI-Konzentrationen.

Summary.A radioimmunoassay has been developed for glucagon. The antibodies raised in rabbits were sensitive to 0.01 ng of glueagon in a volume of 100 ~I. The free and the antibody-bound l~SI-glucagon were separated by addition of ethanol or by paper chromatography on Whatman 3 1VflVI. Two types of antisera were used: one that did not react, with gut GLI (glucagon-like immunereactivity), and another one that reacted with both the pancreatic glucagon and the gut GLI, giving identical dilution curves for the two substances. Exogenous pancreatic glueagon and gut GLI experienced a high degree of degradation during the preparation of plasma unless trasylol was added. A degradation of endogenous pancreatic and gut GLI could also be shown in the absence of trasylol. The damage to 125I-glueagon occurring during incubation in plasma was eliminated by using an easy plasma extraction method yielding an approximately 80% recovery of pancreatic glueagon and gut GLI. Normal human fasting plasma extracts contained 0.26 4-0.024 ng equiv, of pancreatic GLI and 0.384-0.048 ng equiv. of gut GLI (mean of 21 samples ± s.e.m.). During OGTT the pancreatic GLI decreased while the gut GLI increased. The specificity and validity of glueagon determinations are discussed. Mesures, par radioimmunologie, du gIucagon pancrg. atique et du glucagon intestinal contenus dans le plasmaRgsum~. Un dosage radioimmtmologique a dtd dlabor6 pour le glueagon. Les anticorps, provoqugs chez des lapins, 6talent sensibles k 0.01 ng de glueagon dans 100 ~1 de solution. Le l~SI-glueagon, lid ~ l'antieorps, a dtd sdpar6 du l~SI-glueagon libre par addition d'alcool ou par chromatographic sur papier Whatman 3 MNL Deux sortes de sdrum antiglueagon ont dr6 utilisds: l'tm ne rdagit pas avec l'agent intestinal immunoglucagonosemblable (ou GLI intestinal}, l'autre lie aussi bien le glueagon pancrdatique que le GLI intestinal, en donnant des courbes de dilutions identiques. Le glucagon pancrdatique exog~ne et le GLI intestinal exog~ne subissaient une ddgradation trbs pouss~e pendant la prdparation du plasma, sans addition de trasylol. On a pu montrer de m~me une d6na-turation du glueagon pancrdatique et du GLI intestinal endog~ne, en l'absence de trasylol. Aria de prdvenh" route transformation du radio-glucagon pendant l'incubation dans le plasma, on a utilisd une m6thode simple d'extraction du plasma permettant de rdcupdrer ~ peu pros 80% du glneagon pancrdatique et du GLI intestinal. Des extraits plasmatiques, provenant de sujets nermaux et ~ jeun, contenaient 0.264-0.024 ng 6quivalents de GLI panerdatique et 0.384-0.048 ng dquivalents de GLI intestinal (moyenne de 21 dchantillons 4-deart-type de la moyenne). Pendant le test de toldranee au glucose oral (OGTT) on a observ6 une diminution du GLI pancrdatique et nne augmentation simultande du GLI intestinal. La spdcifieitd et la validit6 des mesures du glueagon sent diseutdes. Radioimmunologischs Bestimmung des Pancreas-und Darm-Glucagons im PlasmaZusammenfassung. Es wurde eine radioirnmunologische Bestimmungsmethode fii...

A routing radioimmunoassay for human C-peptide in serum is described. Antibodies against human C-peptide were raised by immunizing guinea pigs with human b-component. Nine out of 12 animals produced useful antibodies within 6 months. Insulin antibodies coupled to Sepharose were used to bind human proinsulin and insulin in the serum and after centrifugation C-peptide was determined in the supernatant. The detection limit of the assay (calculated as 2 SD from zero) was about 0.003 pmole of C-peptide (in 100 mul). The main sources of error were: (1) Normal and diabetic sera devoid of C-peptide gave a displacement of 125I-Tyr-C-peptide varying from 0 to 0.16 nM (6 different antisera). Only one antiserum (M 1181) showed no displacement, and the values of C-peptide determined with this antiserum in normal and diabetic sera were lower than the values determined with another antiserum, which gave a value of 0.07 nM in the sera free of C-peptide. It is suggested that displacement found with most antisera is due to substances in serum that are not related to C-peptide or proinsulin. (2) Serial dilutions of pancreatic extracts and sera may yield dilution curves slightly different to those of the synthetic standard. Possible explanations are discussed. These sources of error can be eliminated or reduced by the proper selection of antisera. Fasting sera from 15 normals, 8 maturity-onset diabetics and 10 insulin-requiring diabetics showed the following concentrations of C-peptide: (M 1181) 0.35 +/- 0.09, 0.74 +/- 0.51 and 0.21 +/- 0.14 (nM, mean +/- SD). One hour after 1.75 g/kg oral glucose the values increased to 2.24 +/- 0.71, 2.34 +/- 0.24 nM.

The plasma C-peptide immunoreactivity (CPR) in 10 normal subjects varied considerably when measured with different antisera in parallel assays. The CPR level correlated with the blank "CPR" value measured in plasma devoid of C-peptide and to a lesser degree with the sensitivity of the standard curves obtained with the individual antisera. Storage of plasma samples at different temperatures and for different lengths of time before the analyses were carried out resulted in further variation in the CPR results. This was caused by a time- and temperature-dependent fall in CPR, which was more pronounced with some antisera than with others. This sensitivity to storage of plasma did not correlate with the antigenic characteristics of the antisera as determined by their reactivity with 11 specific fragments of the C-peptide molecule. The contribution of human proinsulin to the CPR concentration relative in normal subjects was considered to be negligible even though the relative immunoreactivity of human proinsulin and C-peptide ranged from 11 to 143 per cent among these antisera. These results suggest that differences in C-peptide antisera are a major reason for the variation in the concentration of circulating CPR as measured in different C-peptide immunoassays.

A group of 58 diabetics, age 6-17 years and with a duration of diabetes of 3-14 years was studied in order to show whether the nature of the clinical manifestations and the treatment at the onset of the disease are related to the subsequent C-peptide production and also whether remaining C-peptide production is related to better diabetic control. The relations between a number of clinical and laboratory variables were analysed including the degree of ketosis and the insulin dose given at onset of diabetes, the incidence of postinitial remission period, the fasting C-peptide level after the remission period, the level of insulin antibodies and the actual diabetic control expressed as the degree of glucosuria in the patients' urine tests at home. Multiple regression analysis was the main method used. Postinitial remission was positively correlated to initial insulin dose and negatively correlated to duration of ketonuria at onset. C-peptide, which was found in 24.1% of the patients was positively correlated to age at onset and initial insulin dose, but negatively correlated to ketonuria at onset. Diabetic control was positively correlated to insulin dose at onset and to C-peptide level, but negatively correlated to insulin antibodies. It could further be shown that patients who had received a more vigorous treatment immediately at onset had both a higher incidence of postinitial remission and a better diabetic control. The results suggest that an early diagnosis followed by rapid normalization of the metabolism at the onset of juvenile diabetes increase the possibility of preservation of some of the endogenous insulin production, which seems to facilitate diabetic control.

Physical exercise is known to improve glucose tolerance and diminish insulin requirements in patients with well-controlled diabetes mellitus. To ascertain whether these effects of exercise are associated with alterations in insulin receptors, we studied [125I]insulin binding to erythrocytes and monocytes in athletically untrained young men with insulin-treated diabetes during three hours of postprandial bicycle exercise (nine patients) and two hours of exercise during fasting (eight patients). Compared with control periods, postprandial exercise, as well as exercise during fasting, significantly increased insulin binding to erythrocytes and monocytes at an insulin-tracer concentration of 34 pmol per liter. We suggest that similar changes occur in working muscle cells and contribute to the improved glucose tolerance induced by exercise.

Serum C-peptide, insulin-binding IgG and total insulin (IRI) were determined in 96 juvenile diabetics aged 4-21 years, with onset of diabetes at the age of 1-16 years and with 2-17 years' duration of diabetes. Thirty-four patients (35.4%) had detectable levels of C-peptide (greater than or equal to 0.04 pmol/ml). Compared to non-diabetic adults, 19 had values below the normal range, 12 showed values within the normal range (0.18-0.63 pmol/ml) and 3 rated above normal. There was a negative correlation between the fasting C-peptide concentration and the degree of ketonuria at the onset of diabetes and a positive correlation between C-peptide levels and the incidence of post-initial remission periods. Patients without detectable C-peptide had significantly higher levels of insulin antibodies than those who had detectable levels of C-peptide. The possibility of a relationship between the intensity of the initial treatment of diabetes and the preservation of the B-cell function is discussed, as well as the possibility of insulin antibodies being a cause of B-cell exhaustion.

Peripheral hyperinsulinaemia is the cause of metabolic changes that might contribute to the high incidence of macrovascular disease in patients with diabetes mellitus. In order to test this hypothesis muscle biopsies from 12 Type 2 diabetic patients and 14 age and sex matched non-diabetic patients, undergoing minor surgery, were obtained. The diabetic patients had significantly elevated fasting serum insulin (0.29 +/- 0.05 vs 0.06 +/- 0.03 nmol-1) and glucose (8.3 +/- 1.5 vs 4.6 +/- 0.5 mmol-1) and HbA1 levels (8.4 +/- 0.4 vs 5.0 +/- 0.2 per cent). The fasting and 2-h postprandial C-peptide levels were 0.99 +/- 0.25 vs 0.39 +/- 0.12 and 3.12 +/- 0.75 vs 1.09 +/- 0.34 nmol/l, respectively. The diabetic patients showed a marked elevation of triglyceride in the striated muscle biopsies compared to the non-diabetic controls (290 +/- 52 vs 48 +/- 6 mumol/g wet weight, p less than 0.001). Moreover, the activities of glucose-6-phosphate dehydrogenase (0.25 +/- 0.03 vs 0.13 +/- 0.01 U/g wet weight) and malic enzyme (0.15 +/- 0.01 vs 0.05 +/- 0.01 U/g wet weight), necessary for lipid synthesis, were significantly increased (both p less than 0.001) in the diabetic patients while the glycolytic enzymes, hexokinase (0.65 +/- 0.09 vs 1.82 +/- 0.11 U/g wet weight), pyruvate kinase (7.3 +/- 0.9 vs 13.2 +/- 0.9 U/g wet weight), phosphofructokinase (1.3 +/- 0.2 vs 2.6 +/- 0.2 U/g wet weight), and alpha-glycerophosphate dehydrogenase (7.3 +/- 0.5 vs 12.5 +/- 0.7 U/g wet weight) were decreased (all p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)