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In 14 patients with acute pancreatitis during 16 episodes of the disease the concentrations of blood glucose, serum insulin (IRI), C-peptide (CP), and proinsulin (Pro) were determined in the fasting state on d 1, 2, 3, 5, and 10 after the attack. The peptides were measured using RIAs, and for determination of CP two antibodies: Byk-Mallinckrodt's and more specific M-1221 Novo antibodies were used. Apart from sporadic rises in the initial period of the disease, the blood glucose level did not change significantly and had a decreasing trend. On d 1 the mean serum IRI level was 0.17 +/- 0.04 (SD) nM, and it decreased on d 5 to 0.06 +/- 0.04 nM, rising again to 0.11 +/- 0.15 nM on d 10. The serum Pro concentration was on the same days: 11.1 +/- 12.6, 4.2 +/- 2.4 and 7.5 +/- 10.8 pM, whereas the serum CP values determined with M-1221 antibodies were 0.48 +/- 0.50, 0.34 +/- 0.19, and 0.52 +/- 0.25 nM, respectively. However, when serum CP was determined using Byk-Mallinckrodt kits, the concentration on d 1 was 1.90 +/- 1.12 nM and over the following days it decreased to 1.08 +/- 0.98 nM on d 5 and on d 10 it was 1.11 +/- 0.46 nM.(ABSTRACT TRUNCATED AT 250 WORDS)

14 patients with acute pancreatitis during 16 episodes of the disease were studied. The concentration was measured of blood glucose, serum insulin (IRI), serum C-peptide (CP) using two methods: with Byk-Mallinckrodt kits and with more specific M-1221 antibodies Novo, and of serum proinsulin (Pro) in fasting state on days 1, 2, 3, 5 and 10 after the acute onset. Apart from some sporadic rises in the initial period of the disease, the blood glucose level did not change significantly, and had rather a decreasing trend. The mean serum IRI concentration was 0.17 +/- 0.17 (SD) nmol/l, and it decreased on the 5th day to 0.06 nmol/l 0.04 nmol/l, rising again to 0.11 +/- 0.15 nmol/l on the 10th day. The serum Pro concentration was on the same days: 11.1 +/- 12.6, 4.2 +/- 2.4 and 7.5 +/- 10.8 pmol/l, while the serum CP concentration determined with M-1221 antibodies was 0.48 +/- 0.50, 0.34 +/- 0.19 and 0.52 +/- 0.25 nmol/l respectively. However, when for serum CP determinations the Byk-Mallinckrodt kits were used, the concentration of this peptide was on the 1st day 1.90 +/- 1.12 nmol/l, and it decreased over the following days to 1.08 +/- 0.98 on the 5th day, but remained on the same level on the 10th day (1.11 +/- 0.46 nmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

We have investigated whether portal delivery of insulin as a result of intrahepatic islet cell autografts would prevent the development of metabolic alterations. Seven pancreatectomized dogs received islet autografts transplanted into the liver through the portal vein (PD). One year after transplantation, their intravenous glucose tolerance and insulin responses were similar to age-matched control (C) dogs (n = 5). Also, normal triglyceride content in arterial smooth muscle and striated muscle was observed in the dogs with portal insulin delivery in contrast to the substantial increases we observed in pancreatectomized dogs (n = 7) with pancreatic autografts that drained into the systemic circulation (SD). In these dogs, the tissue samples were taken at the age of 3 to 4 years. Triglyceride content (mean +/- SEM) in the aorta was 4.9 +/- 1.2 versus 2.6 +/- 0.6 versus 20.7 +/- 8.0 mumol/g (P less than .01) in C, PD, and SD models, respectively. The corresponding values for triglyceride content in striated muscles were 29.1 +/- 1.2, 25.9 +/- 1.5, and 171.4 +/- 46.6 mumol/g (P less than .01). Glucose-6-phosphate dehydrogenase (G-6-PDH) and malic enzyme, key enzymes for lipid synthesis, were also normal in the PD model, in contrast to the fivefold increased activity of these enzymes in the SD model (P less than .01). The glycolytic enzymes, hexokinase (HK) and phosphofructokinase (PFK), were normal compared with the decreased values in the SD. These data indicate that it is possible to normalize glucose and lipid metabolism in arterial walls by portal delivery of insulin, following intrahepatic islet cell transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

The synthesis of tyrosyl human C-peptide, a sequence of 32 amino acids, by the fragment condensation of the N-terminal octapeptide and C-terminal tetracosapeptide is described. The t-butyl protecting groups were removed by trifluoroacetic acid to obtain N-benzyloxycarbonyl-tyrosyl C-peptide. The hydrogenolytic debenzyl-oxycarbonylation of this derivative proceeded to an extent of only 80-90%, and tyrosyl C-peptide was purified by preparative electrophoresis. This purified tyrosyl C-peptide led to an improved sensitivity of the radioimmunoassay. The synthetic tyrosyl C-peptide in an immunoassay using anti human b-component serum reacted slightly differently from the synthetic human C-peptide. After labelling tyrosyl C-peptide with 125I and then purifying the radioactive product, we observed that 80% of the radioactivity could be bound when reacted with an excess of the serum. The circular dichroism spectrum of tyrosyl C-peptide is very similar to that of synthetic human C-peptide. An analysis of the spectrum indicates that 3-7 amino acids are in the beta-structure and the rest in random coil conformation.

Concentrations of human C-peptide, IRI (immunoreactive insulin) and glucose were determined during oral glucose tolerance test (1.75 g glucose/kg ideal body weight) in 14 normal persons (N), 9 maturity-onset diabetics (DI) and 10 insulin-requiring diabetics (DII) never treated with insulin and in 3 formerly insulin treated diabetics. The mean fasting levels of C-peptide and IRI in the first three groups were: N: 0.37 +/- 0.02 nM and 0.048 +/- 0.009 nM, DI: 0.86 +/- 0.17 nM and 0.11 +/- 0.029 nM, DH: 0.37 +/- 0.04 nM and 0.063 +/- 0.009 nM. One hour after oral glucose ingestion, the respective values increased to: N: 2.53 +/- 0.20 nM and 0.52 +/- 0.077 nM, DI: 2.49 +/- 0.31 nM and 0.49 +/- 0.11 nM, DH: 0.49 +/- 0.05 nM and 0.11 +/- 0.014 nM. Although secreted from the pancreas in equimolar concentrations, the molar ratio of C-peptide to insulin in peripheral blood was about 7 in the fasting state, falling to about 5 in the glucose stimulated condition. Maturity-onset diabetics had higher fasting levels of C-peptide than normal subjects, in agreement with the IRI levels. Three patients previously treated with insulin and having insulin antibodies showed C-peptide responses significantly below the normal range. In one of these patients, the test was repeated 9 months later when the insulin antibodies had disappeared, and the C-peptide response observed at that time was much higher. It is suggested that insulin antibodies cause an impaired IRI - and consequently C-peptide response - by constantly removing insulin from the granules in the B-cell. In normal humans the peripheral C-peptide responses to the oral glucose load showed less relative variation than do the insulin responses. Therefore, a radioimmunoassay for C-peptide in addition to the assay for insulin will provide supplementary information on insulinsecretion.

Neutral soluble human (semi-synthetic) and porcine insulin and diluting medium were administered subcutaneously in a randomized fashion to six fasting normal male subjects. The plasma glucose, C-peptide and insulin response was observed for a period of two hours before and six hours after injection of insulin (0.075 m/kg) into the anterior abdominal wall. The hypoglycaemic response was identical for the two insulins with the plasma glucose values reaching a nadir at 90--120 minutes and returning to within 10% of basal levels by six hours. Also similar peak plasma insulin values were achieved with human and porcine insulin by 50--60 minutes post-injection. The C-peptide response following the administration of both insulins suggested equal suppression of endogenous beta cell secretion. The two insulins were well tolerated with no immediate or delayed allergic reactions in any subject. These results suggest that human (semi-synthetic) and porcine soluble monocomponent insulins under the described experimental conditions are bioequivalent.

Fasting serum C-peptide and total immunoreactive insulin (IRI) were determined in 38 non-diabetic children and adolescents 6-22 years old. C-peptide varied between 0.22-0.73 pmol/ml (mean +/- SD, 0.45 +/- 0.11). There was a tendency to higher values during puberty. No difference was found between subjects with or without a family history for diabetes. IRI varied between 0-31 millimcron/m1 (mean +/- SD, 11.3 +/- 6.5). The C-peptide response to glucagon was studied in 10 insulin dependent juvenile diabetics 11-19 years old, who had had measurable amounts of fasting C-peptide on some occasions during the previous years. Duration of diabetes varied between 4-12 years. A slight but significant rise in C-peptide level occurred in 3 patients. Their metabolic control estimated on the basis of daily urinalysis was "excellent" or "good". The results support the hypothesis that even trace remnants of the beta cell function may be of importance for the metabolic control in juvenile diabetes.

The study was prompted by the apparent detection of insulin antibodies in a black patient with HCC and recurrent hypoglycemia who had never received insulin. It consisted of two parts. Initially the sera of 30 individuals (six normoglycemic HCC patients, three with HCC and recurrent hypoglycemia, 11 patients with noncancerous liver diseases, and 10 healthy black controls) were analyzed for the presence of insulin (and glucagon) antibodies by precipitating the bound, labeled hormone with ethanol and also by the technique of radioimmunoelectrophoresis. In the nine HCC patients, binding of 125I-insulin averaged 13% by ethanol separation and 0.018 mU/ml with radioimmunoelectrophoresis, levels that were similar to those of patients with noncancerous liver disease and significantly higher than those of the healthy controls. Mean binding of 125I-glucagon was 11% in HCC sera. Serum binding of labeled hormones correlated significantly with IgG concentrations in the patients. The second part of the study attempted to define the nature of insulin binding in HCC and other forms of liver disease. After confirmation of the increased serum binding of labeled insulin by another method of precipitation, PEG, an attempt was made to compete with the labeled insulin for its serum binding sites by adding a large amount of unlabeled insulin. This binding was not displaceable, however, and was therefore considered nonspecific. When the same procedures were repeated using normal serum to which increasing amounts of gamma globulin were added, the nonspecific binding of insulin increased in a linear fashion. Furthermore, a similar degree of high nonspecific insulin binding occurred in six patients with multiple myeloma and raised serum IgG concentrations. We therefore conclude that in the many clinical situations where hypergammaglobulinemia exists, false positive tests for the detection of antibodies against insulin (and probably other peptide hormones) will emerge unless appropriate methods are used to check for nonspecific peptide binding.

Plasma concentrations of proinsulin and C-peptide were measured in five children presenting with severe hypoglycaemia associated with elevated plasma levels of immunoreactive insulin (IRI) in order to determine whether the profile of circulating B-cell products related to the underlying pathophysiology of the pancreas. Results were compared with data from 13 normal infants. Four children, three neonates and a nine year old girl, were subjected to partial or total pancreatectomy. The neonates had nesidioblastosis, nesidioblastosis with a microadenoma, and a functional abnormality without histological derangement respectively; the older child had a localised adenoma. The remaining child, a neonate, had transient hypoglycaemia and elevated IRI levels associated with hyperlactataemia and hyperalaninaemia. All the children had markedly elevated plasma proinsulin concentrations; the highest levels were seen in the child with an isolated adenoma and in the neonate with nesidioblastosis and a microadenoma. Both of these children also had substantially elevated plasma C-peptide concentrations. The remaining three neonates had plasma C-peptide levels, which although in the normal range for normoglycaemia were inappropriately elevated during hypoglycaemia. It is concluded that elevated proinsulin and C-peptide concentrations are seen in children with hypoglycaemia associated with increased plasma IRI levels and that the profile of the concentrations does not provide a reliable marker for the nature of the underlying pancreatic abnormality.

Concentrations of ketone bodies, free fatty acids, glycerol, lactate, glucose, insulin, glucagon and cortisol were determined 6-hourly during 36 hours of fasting in 4 hyperthyroid patients and in 4 euthyroid controls. The concentrations of ketone bodies were elevated in hyperthyroid patients from the beginning and increased during fasting more rapidly and to higher values as compared to the controls. After 6 hours of fasting the blood ketone concentrations were 1.1--1.8 mM in hyperthyroid patients and 0.3--0.6 mM in the controls. After 36 hours the concentrations had increased to about 3.5 mM and 1.4 mM in hyperthyroid and control subjects, respectively. The concentrations of free fatty acids were identical in the groups compared postprandially, but increased significantly more in the hyperthyroid patients than in the controls during fasting. The glycerol concentration was higher in the hyperthyroid group throughout the observation period. The concentrations of insulin were slightly higher in the hyperthyroid group than in the control, whereas the concentrations of the "ketogenic" hormones, glucagon and cortisol were identical in the compared groups. It is concluded that hyperthyroidism leads to an increased tendency to ketosis, that is partly explained by increased concentrations of free fatty acids and that might also involve a direct action of long term thyroid hormone excess on enzyme activities (e.g. carnitine acyltransferase in liver).

Abnormal glucose and lipid metabolism in striated muscles and arterial wall has been demonstrated in 3 species: the pig, the dog, and human Type 2 diabetic patients, sharing the common feature of peripheral hyperinsulinaemia. In this study eighteen consecutive patients undergoing coronary bypass surgery and eight control patients were examined. Prior to surgery an oral glucose tolerance test showed that eleven out of eighteen patients had impaired glucose tolerance and significantly elevated fasting immune reactive insulin (IRI) and C-peptide concentrations. There was a statistically significant correlation between the 2 hour blood glucose value and the fasting plasma insulin level (R = 0.55, p less than 0.05). During the operation, aortic and muscle biopsies were taken. The eighteen patients undergoing coronary bypass surgery showed disturbances in glucose metabolism, i.e. decreased activity of glycolytic enzymes (hexokinase 0.30 +/- 0.06 versus 0.40 +/- 0.06 U/g, p less than 0.001, and phosphofructokinase 0.48 +/- 0.09 versus 0.61 +/- 0.07 U/g, p less than 0.01). Malic enzyme activity was increased in all patients (0.17 +/- 0.03 versus 0.06 +/- 0.02 U/g, p less than 0.001). Glucose-6-phosphate dehydrogenase was increased in the eleven patients with impaired glucose tolerance (0.55 +/- 0.10 versus 0.30 +/- 0.07, p less than 0.01) parallel to a significant increase in triglyceride content in the aortic wall (16.1 +/- 4.8 versus 3.7 +/- 3.2 mumol/g, p less than 0.01) as well as in the striated muscles (374 +/- 44 versus 48 +/- 6 mumol/g, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The aim of the present study was to compare the immunogenicity of monocomponent human insulin with that of monocomponent porcine insulin in newly diagnosed Type 1 (insulin-dependent) diabetic children. One hundred and thirty-five patients at diagnosis of diabetes (age 1-18 years, mean age 9.3 years) were randomly allocated to treatment with either Monotard MC + Actrapid MC or Monotard HM + Actrapid HM in a double-blind trial conducted in Sweden, Finland, Norway and Denmark. The human and porcine insulin groups were identical at diagnosis with respect to age, sex and measures of metabolic control. At all times the mean insulin antibody levels and the percentage of antibody-positive patients were lower in the human group compared with the porcine group. At 3 and 12 months, the insulin antibody values were significantly lower in the human group than in the porcine group (p less than 0.05, Wilcoxon's rank sum test). At 12 months, antibody values in the human group ranged from 0 to 1.2 U/l (mean 0.14 U/l) and in the porcine insulin group from 0-5.2 U/l (mean 0.63 U/l). It is therefore concluded that human monocomponent insulin has a lower immunogenicity than porcine insulin of the same purity in newly diagnosed diabetic children during the first year of insulin treatment.

Human insulin derived from porcine insulin was given subcutaneously (s.c.), intramuscularly (i.m.), and intravenously (i.v.) to normal men. The dosage for all three routes was 0 . 075 IU/kg body weight. Diluting medium was administered by s.c. injection to obtain control values. Somatostatin (100 microgram/h) was given to inhibit pancreatic beta cell secretion. The plasma glucose responses to s.c. injection of this insulin into the anterior abdominal wall and to i.m. injection into the thigh were similar with respect to the extent, onset, and duration of effect. Plasma glucose fell from mean (+/- SE) pre-injection values of 4 . 3 +/- 0 . 15 and 4 . 4 +/- 0 . 27 mmol/l, to 3 . 06 +/- 0 . 25 and 2 . 98 +/- 0 . 16 mmol/l by 90 to 105 min for s.c. and i.m. studies, respectively, thereafter returning to mean basal level by 6 h after i.m. injection, but remaining about 0 . 5 mmol/l below basal level after s.c. injection. A much more sudden, but short-lived, hypoglycaemic response occurred after i.v. insulin, with plasma glucose failing from 4. 50 +/- 0 . 42 to 1 . 45 +/- 0 . 16 mmol/l by 25 min, returning to mean basal value after 3 1/2 h. The mean (+/- SE) peak insulin levels after s.c. and i.m. injection were 0 . 13 +/- 0 . 01 and 0 . 18 +/- 0 . 04 pmol/ml at 90 and 60 min, respectively. After i.v. injection the maximum plasma insulin concentration of 6 . 9 +/- 0 . 73 pmol/ml was seen at 2 min. No adverse side-effects were observed.

C-peptide was determined in 24-h urine collections and in fasting plasma of 27 Type 1 (insulin-dependent) diabetic children (duration of disease 0-6 years) and in 11 matched normal children. Grouping the patients according to duration of disease from onset to 6 years, it was found that in the first year of disease the B cell reserve was a mean of 4.89 +/- 1.95 pmol X mg creatinine-1. 24 h-1 compared with a mean of 24.51 +/- 2.91 pmol X mg-1 X 24 h-1 in the control group. A further diminution was seen with increase in the duration of disease, until after 6 years when only traces of C-peptide could be detected. There was a good correlation between the levels of plasma C-peptide and urinary C-peptide values as related to creatinine (r = 0.89; p = less than 0.001). In view of this, and since it is simpler and less traumatic to obtain frequent urine samples from children than it is to obtain blood samples, it was felt that the determination of urinary C-peptide constitutes a valuable tool in the evaluation of the diabetic child.

The plasma glucose, C-peptide and insulin responses to subcutaneously administered highly purified porcine, 'semi-synthetic' and 'biosynthetic' human isophane (NPH) insulin and diluting medium as control in normal male subjects were evaluated. Porcine and semi-synthetic human NPH insulins were administered at two dose levels of 0.15 and 0.30 U/kg body weight and biosynthetic human NPH at 0.15 U/kg body weight only. At the low dose level the three insulin preparations resulted in a similar maximal hypoglycaemic effect within 3-5 h after administration. However, over the remainder of the 11 h post-injection period, the plasma glucose level was lower after semi-synthetic human insulin. In contrast, at the 0.30 U/kg dose level, there was no difference in the early or late hypoglycaemic response between porcine and semi-synthetic human NPH insulins of equivalent pharmaceutical formulation. The clinical relevance of these findings needs further evaluation. The data suggest that for the 'intermediate-acting' NPH insulin preparations, both the species of insulin, nature and quantity of the retarding protein and their subsequent interaction may determine their time-action characteristics.

Two new batches of pancreatic human proinsulin have been compared with biosynthetic human proinsulin. Standards of these three proinsulin preparations were made on the basis of quantitative amino-acid analyses and compared in two proinsulin radioimmunoassays with a proinsulin standard prepared 14 years ago. The curves of the new standards were superimposable. However, they differed considerably from the curve of the old standard which proved to be only one-third of the strength of the new standards, thereby leading to a threefold over-estimation of proinsulin concentrations when the old standard is used. We conclude that the new standards should replace previously used standards.

20 non-diabetic and 11 insulin dependent diabetic (IDD) children underwent short time (20 min) bicycle ergometer exercise followed by a 10 min rest period. Glucose, IRI, C-peptide and proinsulin were determined prior to and at the end of the exercise, and again after 10 min rest. While no significant change in mean glucose was observed during exercise in the non-diabetics, significant decreases were observed in IRI, C-peptide and proinsulin. After 10 min rest glucose as well as the three B-cell secretory products increased significantly. The change in glucose was significantly (p less than 0.001) correlated to the change in IRI. In the resting period IRI rose more than C-peptide in some subjects. IRI even rose without simultaneous rise in C-peptide indicating a release of tissue bound IRI. The group of IDD children did not show any significant changes in glucose and total IRI, while the endogenous insulin, as measured by C-peptide, did show a fall during exercise. The same was found for proinsulin. The lack of increased endogenous secretion during the rest period was most likely due to suppression of B-cell due to hyperinsulinism and lack of increased glucose concentrations during the rest period.

A 16-year-old boy with persistent hyperglycaemia (approximately 16 mmol/l in the fasting state) and acanthosis nigricans had insulin resistance and received daily up to 2800 U of short-acting, soluble, highly purified porcine insulin. The number and affinity of insulin receptors were markedly decreased. No significant insulin binding to IgG could be detected. Immunoreactive insulin varied between 1344 and 2400 mU/l. Endogenous insulin secretion and proinsulin levels were grossly elevated in the fasting state (C-peptide 2.2-3.5 pmol/ml; proinsulin approximately 1 pmol/ml). After an oral glucose tolerance test and intravenous arginine infusion, B cell hypersecretion was confirmed. The molar ratio of C-peptide to immunoreactive insulin, normally approximately 7, was about 0.3, clearly indicating that most of the immunoreactive insulin was exogenous. The molar ratio of proinsulin to C-peptide, which is about 0.05 in fasting control subjects, was 0.23-0.45, clearly showing that too high a proportion of proinsulin was being secreted. This may indicate that the constant hyperstimulation of the B cell leads to reduced conversion of proinsulin to insulin. Immunoreactive glucagon levels were within normal limits fasting but were above normal after intravenous arginine infusion. Thus, in this case of diabetes with acanthosis nigricans, the severe insulin resistance, probably caused by a receptor defect, was associated with markedly increased B cell function.

HLA-types were determined in 102 juvenile diabetics. HLA-B8 was found in 39 patients (RR 2.64; p less than 0.01) and HLA-BW15 in 32 patients (RR 1.33; n.s.). HLA-B7 was found in 14 patients (RR 0.40; p less than 0;05). There were no correlations between HLA-B8 or BW15 and family history of diabetes, occurrence of infection before onset of diabetes, ketonuria at onset or the age at onset of diabetes. Serum C-peptide, insulin binding capacity of IgG and total serum insulin, IRI, were determined in 94 patients who had had diabetes for more than two years and who were beyond the remission period. Measurable amounts of C-peptide were found in 33 patients (34.7%). There was no evidence of a relationship between any particular HLA-antigen and the B-cell function except for an increased incidence of do a decreased incidence of detectable C-peptide in patients with the combination HLA-B8, W15. Only four patients (4.3%) were lacking insulin antibodies; HLA-BW15 positive patients had higher levels of insulin antibodies than other groups, while HLA-B7 positive patients had lower levels; The results suggest that HLA-B7 and HLA-B18 might be associated with a different and perhaps milder form of juvenile diabetes.

The intermediates of the proinsulin-insulin conversion were separated by cation exchange. The circular dichroism spectra of the intermediates showed less alpha-helix than insulin and proinsulin. It is suggested that the C-peptide interacts with the section of alpha-helix contained between residues 2 and 8 in the A-chain of the insulin moieties and unwinds the alpha-helix. The in vivo activities of the intermediates were found to be in the order of 50% relative to insulin. In the fat cell assay, the A-chain-substituted form is weaker (9%) than the B-chain-substituted form (19%). The C-peptide segments of the two forms reacted with C-peptide-specific antibodies as fully as the free C-peptide, on a molar basis. In contrast, the insulin segments were hindered from reacting with insulin-specific antibodies as fully as the insulin.

C-peptide can be used as a measure of endogenous insulin secretion in insulin treated diabetics with insulin antibodies. At the onset of juvenile diabetes insulin production is thought to be absent or minimal, but we have found rather high levels of C-peptide, even in ketoacidotic patients. The ketoacidosis does not mean an irreversible beta cell failure. In the postinitial remission period with stable metabolism many patients have normal or almost normal C-peptide levels and their beta cells have the capacity to respond to natural stimulation with an increased insulin secretion. For some unknown reason the metabolism becomes more labile coinciding with decreasing C-peptide values. However, even several years beyond the postinitial remission period many juvenile diabetics have some persistent beta cell function, and it has been shown that even trace remnants of beta cell function are of importance for stabilization of the metabolism. There is no reason to believe that the beta cell failure should be predetermined e.g. by genetic factors. However, little is known how to influence the progression and stop the increasing beta cell failure. Some of our results suggest that an early detection and an intensive treatment of diabetes before severe metabolic disturbances and pronounced insulin deficiency have appeared, may increase the possibility of preserving some beta cell function.

In 17 type-I diabetic patients on continuous s.c. insulin infusion (CSII) therapy, potential interrelationships between fasting levels of blood glucose (BG), serum free insulin (free IRI), total (free and bound) insulin (total IRI) and insulin-binding immunoglobulin G ( IgGI ) were evaluated. There was no consistent relationship between the basal s.c. infused insulin dosages and the associated insulinaemia or glycaemia. A significant inverse correlation was found between the fasting levels of serum free IRI and BG (P less than 0.005). On the basis of this interrelationship, a target range of 90-110 mg/dl for fasting BG during CSII treatment is proposed.

A comparative study was carried out on B cell response to alternative intravenous glucagon (1.0 mg) and intravenous glucose (0.33 g per kg body weight) in healthy non-obese persons (c-NOb), healthy obese persons (C-Ob), non-obese non-insulin-dependent diabetics (NIDD-NOb) and obese non-insulin-dependent diabetics (NIDD-Ob). Each group comprised ten subjects. C-peptide (CP immunoassay using antiserum M 1230) and IRI in the serum were measured for each test. After glucose load in B-cell responses were significantly lower in both the diabetic groups than in the normal groups. After glucagon injection there were no significant differences in IRI and CP levels between NIDD-NOb and C-NOb, however, significantly lower levels of serum CP were noted among NIDD-Ob in comparison to C-Ob with a lack of these differences in IRI levels. This phenomenon is well reflected by the molar IRI/CP ratio expressed as a percentage. In the fasting state IRI accounted in C-Ob for 8.8 +/- 3.5 per cent of CP, while in NIDD-Ob for up to 25. +/- 10.4 percent of CP (P = 0.0004). In the latter group of patients, the IRI/CP ratio after glucagon reached the highest values (over 30 per cent) observed in this study. These data suggest the important role in insulin disposal played by the liver in non-insulin-dependent diabetes associated with obesity. Another explanation for these data is that more proinsulin is secreted in this group of patients as compared to other groups.

We studied the metabolism and hormone profile of 9 patients with moderately severe acute asthma before treatment, and again 10 min after intravenous aminophylline (250 mg) or the selective beta-adrenergic stimulant hexoprenaline (5 microgram) intravenously. Compared with basal values in normal subjects the untreated asthmatics had statistically significant raised mean plasma pancreatic glucagon, free fatty acid (FFA) and glucose levels in the plasma and a significantly depressed mean plasma potassium level. Insulin, growth hormone, cortisol, thyrotropin and ketone body levels were normal. The only significant changes after therapy were a further fall in plasma potassium in the hexoprenaline-treated patients and a rise in the mean lactate concentration of the group as a whole. The clinical implications of these findings are briefly considered.

The levels of proinsulin, immunoreactive insulin, true insulin (calculated from the difference, namely immunoreactive insulin-proinsulin) and C-peptide were determined in the fasting state and during a 3-h oral glucose tolerance test after administration of 100 g of glucose in 12 patients with cirrhosis with normal oral glucose tolerance test (50 g) and in 12 healthy subjects serving as controls. In the patients with cirrhosis the serum levels of proinsulin and immunoreactive insulin were significantly higher in the fasting state and after glucose loading than in the healthy subjects. The serum level of true insulin was also higher in the patients with cirrhosis, but the difference was less pronounced and only significant at a few of the time points. The serum level of C-peptide was very similar in both groups. These results emphasize that cirrhosis is a condition in which the serum proinsulin level is raised and that this hyperproinsulinaemia contributes greatly to the increased immunoreactive insulin levels observed in patients with this disease.

Weak nonspecific immunological stimuli can irritate the glomerular mesangium as observed following administration of insulin preparations of varying degrees of purity. In the present study further substances were investigated with regard to this effect. We wished to examine which substances obtained during purification of insulin are mainly responsible for the antigenicity, and whether porcine and bovine MC insulin have the same antigenic properties. Rabbits were treated for up to 90 days with bovine MC insulin, bovine proinsulin, bovine a + b-component, porcine a-component and porcine b-component. The kidneys were analysed morphometrically and antibody titers to bovine insulin, a-component, porcine PP and proinsulin were determined in the various test groups. It was found that bovine MC insulin and porcine MC insulin possess the same immunological activity, i.e. no antibody formation to either of the two insulins was demonstrable. Similarly, there were no differences in the morphometric findings; slight transient mesangial changes were demonstrable after both insulins. However a-component and b-component showed a pronounced immunogenic potency with antibody formation. Marked and partly persisting mesangial alterations were demonstrable, with the antigenicity of the a-component being particularly marked. The implication of the study is that a "pure" or optimally purified insulin should be used in the therapy of diabetes mellitus.

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.

Five patients with mild maturity-onset diabetes were given 250 ml of a 20% glucose solution by intraduodenal infusion and eight other patients similarly received an amino acid solution in a dose of 0.5 g amino acids per kg body weight. The pancreatic and gut glucagon-like immunoreactivity (pancreatic GLI and gut GLI) in plasma were measured before and after the application of the two stimuli. Each person was tested twice; the first (control) test was followed by a second test after three days of treatment with phenformin 150 mg daily, plus the same 150 mg dose taken 60 min before the intubation. The plasma pancreatic GLI increased slightly during both infusions, but was not affected by phenformin. Intraduodenal infusion of both glucose and the amino acid solution induced a greater rise in plasma gut GLI. After treatment with phenformin, the fasting plasma gut GLI was higher than the control value in eleven of thirteen patients. In most cases higher gut GLI plasma levels were also found after duodenal administration of glucose and amino acids. These data furnish further evidence of the local action of antidiabetic biguanides on the intestinal wall, including its hormonal activity. The hypothesis is advanced that the phenformin-induced increase in gut GLI secretion may bring about competition of the latter with pancreatic glucagon for receptors in liver cell membranes, reducing the effect of glucagon on the liver, and thus contributing to a decrease in glycaemia.

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.

Six normal subjects received subcutaneous human, porcine, and bovine ultralente insulin (0.30 U/kg) and diluent (control) in randomized order. Plasma glucose, C-peptide, and insulin were measured for 32 h after injection. From 10 h onward human ultralente produced significantly lower plasma glucose levels (p less than 0.05-0.01) compared to bovine ultralente. Porcine ultralente produced an intermediate hypoglycaemic response up to 16 h and was similar to the bovine insulin from 24-32 h. Estimated exogenous insulin concentration was higher (p less than 0.05-0.001) following human ultralente compared to bovine ultralente between 2 and 22 h after injection. Up to 24 h the porcine preparation led to intermediate insulin levels, but becoming identical to bovine ultralente from 28-32 h. Peak mean exogenous insulin values for human, porcine, and bovine ultralente were 0.054, 0.044, and 0.023 nmol/l at 14, 16, and 18 h, respectively, reaching 0.022, 0.013, and 0.013 nmol/l at 32 h. The different pharmacokinetic behaviour of human and bovine ultralente insulin must be considered when initiating treatment with human ultralente or transferring patients from bovine to human ultralente.

Basal fasting values of plasma C-peptide (CP), plasma insulin and 24 h urine CP were determined in 224 normal non-obese subjects of both sexes ranging in age from 1 to 20 years. Analysis of the results by age, pubertal rating, sex and bone age (BA) during childhood showed that mean +/- SD plasma CP levels in both sexes rose from 0.07 +/- 0.08 pmol/ml at the age of 1-2 years to 0.21 +/- 0.11 pmol/ml at 8-10 years. Mean +/- SD plasma insulin levels in both sexes rose from 3.2 +/- 4.3 microU/ml at the age of 1-2 years to 5.9 +/- 4.5 microU/ml at 8-10 years. Mean +/- SD urine CP levels rose from 6.5 +/- 2.8 pmol/mg creatinine per 24 h at the age of 2-8 years to 7.7 +/- 3.5 pmol/mg creatinine per 24 h at 8-11 years in both sexes. During puberty, plasma and urine CP and plasma insulin levels rose further to peak at pubertal stage P3, the values in females being higher (CP = 0.32 +/- 0.06 pmol/ml) than those in males (CP = 0.22 +/- 0.06 pmol/ml) (P less than 0.005). Plasma insulin levels in females were 13.2 +/- 6.9 microU/ml and 6.4 +/- 3.1 microU/ml in males (P less than 0.05). Urine CP levels were 14.5 +/- 5.7 pmol/mg creatinine per 24 h and 10.8 +/- 5.4 pmol/mg creatinine per 24 h in females and males respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Highly purified neutral soluble human, porcine and bovine insulin (0.075 U/kg body weight) were administered randomly by subcutaneous injection to six normal men. Somatostatin by continuous intravenous infusion (100 micrograms/h) was used to suppress endogenous insulin secretion. The effects of the three species of insulins on plasma glucose, immunoreactive insulin (IRI), C-peptide and intermediary metabolite concentrations were essentially similar. The onset of hypoglycaemic action of bovine insulin was delayed compared to human and porcine insulin due possibly to a lower receptor binding of the bovine insulin. No local or systemic adverse reactions to the insulins were observed.

The safety and efficacy of a new highly purified neutral soluble human insulin produced by conversion of porcine insulin was compared with a highly purified neutral soluble porcine insulin in six normal men. The insulins were administered by subcutaneous injection at a dose of 0.075 U/kg body weight. Somatostatin was infused during the experiment to suppress endogenous insulin secretin. No difference was found in the plasma glucose, insulin, or metabolite responses. Thus the potency, onset, and duration of effect were identical with the two insulins. No short-term side effects to either insulin were observed. Highly purified, semi-synthetic human insulin offers a safe and effective means to explore the possible advantages of homologous human insulin in the management of diabetes mellitus.

The plasma insulin, C-peptide and proinsulin concentrations were investigated in thyrotoxic patients and in normal controls after an overnight fast, during a 36 h fasting period, an intravenous glucose tolerance test and an oral glucose tolerance test. The main finding was a significantly raised concentration of proinsulin in plasma of patients with thyrotoxicosis. After an overnight fast the plasma proinsulin was 0.048 +/- 0.005 pmol/ml in 15 thyrotoxic patients compared with 0.023 +/- 0.012 pmol/ml in 15 euthyroid controls. A twofold rise of plasma proinsulin concentration was also found in thyrotoxic patients during a prolonged fast, and during intravenous and oral glucose tolerance tests. The immunoreactivity of proinsulin in the insulin radioimmunoassay gave rise to slightly elevated concentrations of immunoreactive insulin in thyrotoxic patients in all the conditions investigated. When insulin values were corrected for proinsulin crossreactivity, they were similar in euthyroid controls and thyrotoxic patients. The concentration of plasma C-peptide was not significantly altered in thyrotoxic patients during intravenous and oral glucose tolerance tests.