Normalization of the paradoxic secretion of glucagon in diabetics who were controlled by the artificial beta cell.

Since it is important to elucidate the precise significance of pancreatic A-cell hypersecretion in the pathogenesis of diabetes mellitus, the change in the immunoreactive glucagon (IRG) response to 100 g oral glucose challenges was studied in diabetics whose blood glucose responses and plasma immunoreactive insulin concentrations (IRI) simulated those in normal subjects with the aid of the artificial beta cell system that we developed originally. In six nonobese adult-onset and four insulin-dependent diabetics whose blood glucose responses and plasma insulin concentrations after 100 g oral glucose load were made equivalent to those seen in normal subjects by the artificial beta cell, the glucagon release was similar to the response in normal subjects. In one insulin-dependent diabetic with high anti-insulin-binding capacity, the blood glucose response after an oral glucose challenge was not normalized by the artificial beta cell and the glucagon secretion was paradoxically increased. This fact suggested that the paradoxic rise in glucagon, seen in response to an oral glucose load in some diabetics, is secondary to insulin deficiency.     

Carbohydrate metabolism and pancreatic islet-cell function in thalassemia major.

To investigate the development of diabetes mellitus in patients with thalassemia major, plasma glucose and immunoreactive insulin (IRI) levels following oral glucose and intravenous tolbutamide and glucose disappearance rates following intravenous insulin were measured in 10 patients before and during five years on a high transfusion program (HTP). Plasma immunoreactive glucagon (IRG) levels following oral glucose, intravenous insulin, and arginine were measured during the sixth year. Serial percutaneous liver biopsies were performed on seven patients. The oral glucose tolerance tests (OGAT) and mean peak IRI levels were normal in nine of 10 patients before HTP. After HTP was begun a progressive deterioration of OGTT occurred despite normal IRI levels. Following tolbutamide, the mean per cent fall in plasma glucose in the patients before HTP was significantly less than in controls (p less than 0.01) and similar to that of controls during five years of HTP in spite of higher than normal peak IRI levels. Of seven survivors after six years of HTP, three had normal OGTT and four had chemical diabetes; mean peak IRI levels were normal, but fasting IRG levels were significantly higher than in controls (p less than 0.05). In all seven patients, plasma IRG failed to increase following insulin-induced hypoglycemia and was significantly higher than in controls after arginine (p less than 0.01); after oral glucose, plasma IRG fell significantly below that of fasting only in the patients with chemical diabetes (p less than 0.03). Following intravenous insulin, the mean per cent fall in glucose before and during HTP was significantly less than in controls (p less than 0.01). Hemosiderosis and cirrhosis were present in all biopsied patients. Four patients died; two had chemical and two had nonketotic insulin-dependent diabetes. These data suggest that diabetes mellitus occurs frequently in patients with thalassemia on HTP and that insulin resistance and hyperglucagonemia, possibly due to cirrhosis, are important etiologic factors.     

The role of gastric glucagon immunoreactivity in pancreatectomized dogs

Immunoreactive glucagon (IRG) or glucagon immunoreactivity is known to be increased in the plasma of insulin-deprived pancreatectomized dogs, most of it originating in the stomach. We attempted to clarify the extent to which gastric IRG is involved in glycogenolysis in the liver of insulin-deprived, pancreatectomized dogs. Mongrel dogs underwent total pancreatectomy. IRG levels in portal vein blood increased to 760±186 pg/ml on the 4th postoperative day while the insulin levels were negligible. On the 4th postoperative day some of the dogs underwent total gastrectomy. IRG levels in the portal vein blood of pancreatectomized dogs decreased from 760±186 pg/ml to 135±44 pg/ml one hour after gastrectomy. Glucose containing insulin was then infused into both panreatectomized and pancreatectomized-gastrectomized groups of dogs. Glycogen synthesis in the liver during glucose and insulin infusion was much the same in both groups. However, glycogen degradation after glucose and insulin infusion was completely suppressed in pancreatectomized dogs without a stomach while pancreatectomized dogs alone showed marked glycogenolysis in the liver. No difference in portal IRI and blood sugar level was found in both groups while a marked difference in portal IRG were observed. These findings indicate that the IRG released from the stomach plays a significant role in glycogen metabolism in pancreatectomized dogs. Supported by a Grant in Aid for Scientific Research (248257 for 1977) from the Ministry of Education, Japan.     

Remission of hypoglycemia after partial resection of a metastatic islet cell tumor.

The course of a malignant islet cell tumor, producing increased levels of both insulin and glucagon, was studied clinically and in vitro for two years. The patient presented with hypoglycemia, and extensive hepatic metastases were present. Instead of biopsy alone, it was elected to remove the primary in the tail of the pancreas, and subtotal pancreatectomy was performed. There followed a six month interval without hypoglycemia, during which immunoreactive insulin (IRI) decreased (though remaining elevated) and immunoreactive glucagon (IRG) increased markedly. The tumor and a liver metastasis contained elevated IRI and IRG with immunofluorescence for insulin, though typical beta and alpha cells were not present on electron microscopy. A preparation of a monolayer culture of a liver metastasis decreased its IRI production with a similar time course to the clinical improvement, though rapid cell growth continued. Streptozotocin in vitro was markedly cytotoxic. In vivo Streptozotocin caused tumor regression, increase in fasting plasma glucose, decrease in plasma IRI and IRG, and improvement of glucose tolerance. Thus, this case showed elevated IRG in plasma and tumor, improvement in glucoregulation upon excision of the primary, and both in vitro cytotoxicity and clinical improvement with Streptozotocin. It is suggested (1) that cases refractory to therapy directed toward suppression of insulin secretion might benefit from removal of the primary and (2) that further use of cultures of such tumors should be initiated to establish whether they might be useful for predicting in vivo effectiveness of cytotoxic agents.     

Synthetic gastric inhibitory polypeptide. Stimulatory effect on insulin and glucagon secretion in the rat.

Effect of synthetic gastric inhibitory polypeptide (GIP) on insulin and glucagon secretion was stuied in vivo and in vitro in the rat. Intravenous administration of 1 microng./kg. GIP along with 0.625 gm./kg. glucose caused a more prominent rise of plasma insulin than did 0.625 gm./kg. glucose alone. The suppression of plasma glucagon levels induced by glucose was attenuated partially but not significantly by the concomitant administration of GIP. GIP (1 microng./kg. i.v.) alone raised both plasma insulin and glucago levels. In in-vitro experiments with isolated pancreatic islets, GIP significantly augmented insulin release induced by either 8.3 mM or 16.7 mM glucose, whereas the augmentation of glucagon release was observed at 3.3 mM, 8.3 MM, and 16.7 mM glucose concentrations. Three peptides, consisting of 1-28, 22-43, and 15-43 amino acids of GIP, failed to potentiate insulin and glucagon secretion. These results suggest that synthetic GIP has a stimulating effect on insulin and glucagon secretion.     

Effects of ingestion of triglyceride or galactose on secretion of gastric inhibitory polypeptide and on responses to intravenous glucose in normal and diabetic subjects

Responses of plasma immunoreactive gastric inhibitory polypeptide (IRGIP) to oral triglyceride or galactose were compared in normal and mildly diabetic (non-insulin-dependent) subjects. After triglyceride the responses of IRGIP were similar, but after galactose those of the diabetics were slightly exaggerated. Both stimuli evoked increments of plasma immunoreactive glucagon (IRG) in diabetics but not in normal subjects. Plasma immunoreactive insulin (IRI) did not change. In normal subjects given oral triglyceride or galactose followed by intravenous (I.V.) glucose the early-phase response of plasma IRI was enhanced and glucose tolerance improved. In the diabetics, oral triglyceride did not affect insulin release or glucose tolerance after I.V. glucose; oral galactose elicited a slight increase of insulin release without improving glucose tolerance. In the diabetics the rise of plasma IRG after ingestion of triglyceride or galactose was maintained after I.V. glucose. It is concluded that endogenous GIP is insulinotropic and that there is partial resistance to this action in diabetes. The results were compatible with feedback inhibition of GIP secretion by insulin and with the suggestion that the rise of plasma IRG associated with secretion of GIP in diabetics may be due to the glucagonotropic action of this peptide.     

Effect of somatostatin on blood sugar, plasma growth hormone, and glucagon levels in diabetic children.

In nine children with clinically overt insulin-dependent diabetes mellitus the authors injected cyclic somatostatin (3 mug./kg. bolus, followed by infusion of 13 mug./kg. in 60 minutes) and measured blood glucose, plasma growth hormone, and glucagon concentrations throughout the infusion. The rapid administration produced no significant changes of these parameters. With the prolonged infusion there was a significant reduction of blood glucose from a mean of 148 +/- 19.7 to a mean of 88.5 +/- 18.1 mg./100 ml. (P less than 0.005) and of plasma glucagon from a basal mean of 33.3 +/- 2.4 to a minimum mean of 22.1 +/- 1.7 pg./ml. (P less than 0.01). There was a statistically significant correlation between the two parameters (0.01 less than P less than 0.05). Plasma GH values also diminished during the infusion, but the reduction was not statistically significant. These results show that somatostatin lowers blood glucose concentrations as a secondary effect of inhibition of glucagon secretion. Somatostatin is not suitable for therapy in diabetes. We speculate that a similar substance with a more prolonged and specific action on glucagon might prove of practical value in the treatment of diabetes mellitus.     

Effects of total pancreatectomy on the secretion of gut glucagon in humans

To determine how total pancreatectomy influences the secretion of gut glucagon in man, 15 totally pancreatectomized patients (Px), 14 distally gastrectomized patients (Gx), and 15 healthy subjects were investigated by intravenous arginine infusion test and oral glucose tolerance test. Blood glucose, plasma insulin (IRI), and C-peptide (CPR) levels were determined. Plasma immunoreactive glucagon (IRG) and total glucagonlike immunoreactivity (total GLI) were also measured. Gut glucagon-like total GLI and IRG. In the Px group, arginine infusion did not significantly alter the levels of IRI, CPR, IRG, and gut GLI. Mean basal value of gut GLI in the Px group of 356±40 pg/ml was significantly higher than 179±26 pg/ml of the healthy (p<0.01) and 182±24 pg/ml of Gx group (p<0.01). Oral glucose loading led to the highest increase of gut GLI in the Px group (p<0.01). Thus, extrapancreatic IRG may not be secreted into the plasma in totally pancreatectomized humans in response to arginine stimulation. Complete absence of the pancreas and the deficiency of insulin-effect may lead to a hypersecretion of gut GLI, both in the basal state and after oral glucose loading.     

Studies on the mechanism underlying the influence of alanine infusion on glucose dynamics in the dog.

These experiments have been designed to study the influence of alanine infusion of glucose dynamics in the dog and to further elucidate the role of pancreatic hormones in the interaction of alanine with glucose homeostasis. The primed constant infusion of glucose-2-t was used in order to quantitate the rates of glucose production by the liver (Ra) and glucose utilization (Rd). In a first group of experiments, the intravenous infusion of alanine at the rate of 2 mg./kg./min. produced a moderate enhancement of plasma insulin (IRI), while pancreatic glucagon (IRG) increased more consistently. This different pattern of IRI and IRG response caused the insulin/glucagon molar ratio to decline progressibely throughout the experiment. Both rates of glucose turnover increased significantly during alanine infusion. Since Ra rose more rapidly thanRd did initially, hyperglycemia developed. Later, glucose production slowly decreased and, in spite of the sustained hyperglucagonemia, reached levels very close to the baseline in the second part of the experiment. A significant direct correlation between Ra and IRG was found, while the changes in Ra correlated inversely with those in I/G molar ratio. In a second group of experiments, alanine was infused at the same dose together with 0.4 microng./kg./min. of cyclic somatostatin. In the first part of the infusion, IRG fell more than IRI did, so that I/G ratio increased. Later, IRI levels maintained at low values while IRG returned slowly to the baseline and consequently I/G ratio significantly decreased. Glucose production fell rapidly soon after the beginning of the infusion, and therefore hypoglycemia developed. Later, Ra increased progressively to levels above baseline and plasma glucose returned to the preinfusion levels. As in the the first group of experiments, a significant direct correlation between Ra and IRG and an inverse correlation between the changes in Ra and I/G ratio were observed. These experiments demonstrate that alanine infusion produces an acceleration of glucose turnover and that a clear interrelationship between the release of glucose by the liver and the mobilization of pancreatic hormones exists. Finally, the experiments with somatostatin indicate that hyperglucagonemia is one of the mechanisms underlying the stimulatory effect of alanine on glucose production.     

An appraisal of radical pancreatoduodenectomy based on glucagon secretion.

In an attempt to elucidate changes in endocrine functions of the pancreas associated with radical pancreatectomy for periampullary cancer, plasma levels of insulin (IRI) and pancreatic glucagon (IRG) were measured during arginine infusion in ten patients with periampullary cancer both before and after pancreatoduodenectomy. The response of plasma IRI to arginine which was impaired before the surgery showed further impairment after the surgery. This finding is consistent with the previous results obtained in such patients by oral glucose tolerance testing. Also, the response of plasma IRG was subnormal preoperatively and was found to be impaired postoperatively. Both maximum and integrated secretion of IRG during arginine infusion decreased after the surgery in all instances. From these findings, it is concluded that pancreatoduodenectomy aggravates the already disordered pancreatic endocrine functions, as indicated by arginine infusion in patients with periampullary cancer.     

Insulin and glucagon secretion after pancreatectomies. Correlation of secretion and hormonal contents of remaining pancreas

We studied whether insulin and glucagon secretory capacities change in relation to the corresponding hormonal contents in the pancreas remnant after pancreas resection. The following groups of dogs were used: sham operated (S-O), left pancreatectomized (L-Px), right pancreatectomized (R-Px), subtotal pancreatectomized (St-Px), and total pancreatectomized (T-Px). Endocrine functions were assessed by intravenous glucose tolerance test (IVGTT) and insulin tolerance test (ITT) in each dog under anesthesia before surgery and 1 wk after. In these five groups, the insulin secretory capacities, assessed as the integrated incremental secretion of immunoreactive insulin (sigma delta IRI) from the IVGTT, decreased to 95 +/- 11, 78 +/- 9, 48 +/- 8, 12 +/- 8, and -4 +/- 4% of the respective preoperative values, and these values were proportional to the percentage residual weight (100, 64 +/- 2, 35 +/- 2, 13 +/- 2, 0%) and IRI content (100, 59 +/- 4, 45 +/- 3, 10 +/- 2, 0%) of the pancreas remnant. After surgery, glucagon secretory capacity, the integrated incremental secretion of immunoreactive glucagon (sigma delta IRG) during the ITT, decreased significantly in the L-Px, St-Px, and T-Px groups but not in the R-Px group. The sigma delta IRG values as percentages of the preoperative values were 109 +/- 25, 46 +/- 11, 89 +/- 13, 19 +/- 11, and 3 +/- 3%, respectively, for the five groups. These values were proportional to the percentage residual IRG contents of the pancreas remnants (100, 48 +/- 6, 65 +/- 8, 12 +/- 2, 0%) rather than to the percentage residual pancreatic weights.(ABSTRACT TRUNCATED AT 250 WORDS)     

Suppression and stimulation mechanisms controlling glucagon secretion in a case of islet-cell tumor producing glucagon, insulin, and gastrin.

The mechanisms controlling secretion of glucagon and other pancreatic hormones were studied in a patient affected with multihormone-secreting islet-cell tumor. Fasting glucagon levels (3,000 pg./ml.) rose to 10 ng./ml. following arginine stimulation. While oral glucose load and intravenous glucose infusion did not suppress glucagon secretion, insulin administration induced a prompt depression in glucagon levels. Glucagon, insulin, and gastrin levels were suppressed by somatostatin while calcium infusion caused a paradoxical increase. It is suggested that only some of the stimulation-inhibition mechanisms were conserved in this case of glucagon-secreting pancreatic tumor.     

Reciprocal gastropancreatic modulations for the release of somatostatin-like immunoreactivity, glucagon, and insulin in the rat

In order to assess the interrelationships between stomach and pancreas regarding the secretions of somatostatin-like immunoreactivity (SLI), glucagon (IRG), and insulin (IRI), concentrations of the three hormones were assayed in portal plasma and portal blood flow was measured in enterectomized rats before and after the selective removal of stomach or pancreas. Portal plasma SLI, IRG, and IRI concentrations were significantly increased by i.v. arginine in control rats (pancreas + stomach present). After gastrectomy, SLI, IRG, and IRI concentrations were, respectively, 52 +/- 13% (N = 15; P less than 0.005), 234 +/- 40% (P less than 0.001), and 119 +/- 15% (NS) of the pregastrectomy values. A decreased SLI secretion, an increased IRG release, and an unmodified basal IRI release were estimated by portal flow measurement. The A- and B-cell responses to arginine in the gastrectomized rats were significantly higher than in the control rats, while the D-cell response was no longer detectable. After pancreatectomy, by contrast, SLI concentrations were 360 +/- 75% of the prepancreatectomy values (N = 12; P less than 0.001). This reflected an actual increment of SLI release, taking into account the concomitant measurement of portal blood flow. The concentrations of IRG declined by 51 +/- 5% (P less than 0.001) and IRI was no longer measurable. A- and B-cell responses to arginine also were no longer detectable. These results suggest that in these experimental conditions (1) the stomach restrained pancreatic A- and B-cell responses to arginine, perhaps through the SLI released from the stomach and (2) the pancreas restrained gastric SLI secretion, perhaps through insulin.     

Plasma immunoreactive insulin (IRI) and immunoreactive glucagon (IRG) after evisceration with and without a functional liver.

Fed male Wistar rats were eviscerated by two procedures. The first group of eviscerated rats were left with a nonfunctional liver in situ while the second group were eviscerated by a newer technic, developed in this laboratory, that preserves liver function. The animals were maintained on a regimen of saline and antibiotic treatment, and abdominal aortic blood was drawn at intervals up to seventy-two hours postoperatively from animals with a functional liver and up to six hours postoperatively in those with nonfunctional liver status. Blood concentrations of glucose, immunoreactive insulin, and immunoreactive glucagon were measured. Our results indicate that even with a functional liver, totally pancreatectomized eviscerated rats maintained normal amounts of plasma IRI and IRG for more than twenty-four hours. IRI and IRG were measurable even at forty-eight hours postoperatively. At the same time, these animals developed abnormally high blood glucose levels, which were sustained despite the presence of "normal" IRI in plasma. It had been suggested that the presence of measurable IRI and IRG in the classically prepared eviscerated animal was due to a deficit liver destruction of these substances. To the contrary, our data suggest that even with a functional liver, the eviscerated preparation maintains a circulating level of insulin and glucagon-like materials forty-eight hours after the known sources of such substances are removed. The physiologic meaning of immunoassay results following pancreatectomy are thus difficult to interpret.     

Arginine-stimulated acute phase of insulin and glucagon secretion. I. in normal man.

To document and characterize the immediate phase of glucogen secretion as detected in peripheral blood in man, we have given pulses of L-arginine (0.1 gm. to 10.0 gm.) intravenously over twenty to thirty seconds to twenty-three healthy young men. Peak glucagon and insulin levels averaging four and five times basal levels respectively were reached two to five minutes after arginine administration and had returned to baseline levels by fifteen to thirty minutes. Computing the area above basal for the initial ten minutes after arginine stimulation established a dose-response relationship for the acute phases of glucagon and insulin secretion. A maximal glucagon response was elicited by doses of arginine of 5.0 gm. or greater, whereas for insulin, the plateau was reached at 2.5 gm. of arginine. Sequential 5.0-gm. pulses of arginine administered every thirty minutes showed that there was no augmentation or attenuation of the timing, magnitude (area 0-10 minutes) or absolute peak values reached for either the glucogon or insulin responses. The effect of induced hyperglycemia on the acute phase of insulin and glucagon secretion was assessed by administering the arginine during marked elevation of ambient glucose concentration achieved by the intravenous administration of glucose. This resulted in marked suppression of the acute glucagon response and dramatic accentuation of the insulin response.     

Tumor hypoglycemia: deficient splanchnic glucose output and deficient glucagon secretion.

Fasting hypoglycemia occurred in a patient with a histologically benign mesothelioma; the serum insulin was low (2-4 muU./ml.), as was the glucose utilization rate. Splanchnic glucose output was markedly decreased on direct measurement (21 mg./min.; normal: 108-180 mg./min.). Splanchnic uptake of gluconeogenic substrates plasma glucagon was low normal during hypoglycemia and responded poorly to oral and intravenous alanine. The nonsuppressible insulin-like (NSILA-s) and somatomedin-like activities of the serum were not elevated, and the tumor did not release insulin-like activity on incubation nor did it contain somatostatin. The marked decrease in splanchnic glucose output was the principal cause of hypoglycemia, was associated with an apparent decrease in glycogenolysis, and was at least partly due to deficient glucagon secretion. The relationship of the tumor to these defects is unclear. The tumor may have secreted an unknown insulin-like material affecting primarily the liver and/or pancreatic alpha cell. The approach used here may serve as a paradigm for the analysis of hypoglycemia not caused by excessive insulin.     

Prostaglandin synthesis inhibitors impair hepatic glucose production in response to glucagon and epinephrine stimulation

To investigate whether inhibition of prostaglandin synthesis affects hormone-induced glucose dynamics, we measured glucose turnover in response to glucagon alone (5 ng . kg-1 min-1) or combined with epinephrine (0.1 microgram . kg-1 min-1) in conscious trained dogs (N = 6) on three separate occasions in each animal: (1) during a control saline infusion, (2) during infusion of indomethacin, and (3) during infusion of sodium salicylate. Glucose production (Ra) and utilization (Rd) were determined by isotope dilution using the nonrecycling label 3-3H glucose. In controls, glucagon levels (IRG) rose from a basal of 44 +/- 12 to 260 +/- 40 pg/ml (mean +/- SEM) during glucagon infusion; basal epinephrine levels (EPI) of 150 +/- 20 pg/ml were unaffected by glucagon infusion but rose four- to fivefold during combined glucagon/epinephrine infusion. Plasma glucose rose transiently from 95 +/- 1 to a peak of 136 +/- 13 mg/dl after 20 min of glucagon; infusion of EPI resulted in a second glycemic response with a peak of 148 +/- 9 mg/dl. Ra increased transiently from 2.9 +/- 0.2 to a peak of 7.9 +/- 1.4 mg . kg-1 min-1 during glucagon alone with a second rise to 6.2 +/- 0.8 mg . kg-1 min-1 10 min after beginning EPI. With glucagon alone, Rd paralleled Ra but addition of EPI resulted in a relative fall in Rd. Insulin (IRI) rose from 9 +/- 1 microU/ml to 29 +/- 6 microU/ml with glucagon but IRI fell despite the second glycemic response during EPI. When either indomethacin or salicylate was infused, basal IRI, IRG, EPI, glucose, Ra and Rd were unaffected and were similar to controls. Although plasma levels of IRG and EPI during glucagon or glucagon plus epinephrine infusion were also similar to controls, the glycemic response was reduced (P less than 0.05). This attenuation of glycemic response was due to a reduction of stimulated Ra (P less than 0.05) and not to an increase in Rd. Changes in IRI paralleled the reduction in glycemic response. Thus, both indomethacin and salicylate blunt the glycemic response to glucagon and glucagon plus epinephrine by attenuating glucose production and not by enhancing glucose utilization or insulin secretion. These results with two prostaglandin synthesis inhibitors suggest that prostaglandins modulate the hepatic effects of glucagon and epinephrine.     

Differential sensitivity of glycogenolysis and gluconeogenesis to insulin infusions in dogs.

The suppressive effect of insulin on hepatic glucose production is generally recognized. Though it is well established that this effect is at least partially due to inhibition of glycogenolysis, controversy still exists about insulin's effect on gluconeogenesis. The present study was undertaken to determine whether insulin could affect gluconeogenesis from alanine in the intact dog and to compare the effect of insulin on glycogenolysis and gluconeogenesis. In anesthetized dogs fasted overnight, blood samples were drawn simultaneously from a femoral artery and hepatic vein. Alanine-U-14C, 10 mu Ci./kg., was infused over 110 minutes. A constant insulin infusion at either 1 or 5 mU./kg./min. was begun at 50 minutes, and blood glucose concentration was maintained by a variable glucose infusion. When insulin was infused at 1 mU./kg./min., resulting in plasma immunoreactive insulin (IRI) levels of 73 +/- 10 muU./ml., the net splanchnic glucose production (NSGP) was suppressed from 2.7 +/- 2 mg./kg./min. to virtually zero. In constrast, this small increment in insulin concentration had no demonstrable effect on the net splanchnic uptake of alanine or on the conversion of plasma alanine to glucose (7.9 +/- 0.3 mu mol/min.). Insulin infused at 5 mU./kg./min. resulted in IRI levels of 240 +/- 25 muU./ml. This higher insulin concentration was associated with a marked suppression of both the NSGP (100 per cent) and the conversion of plasma alanine to glucose (90 per cent) but did not affect the extraction of alanine by the splanchnic bed. Doses of both 1 and 5 mU./kg./min. were associated with a 35 per cent fall in immunoreactive glucagon levels. These data demonstrate that (1) glycogenolysis is more sensitive than gluconeogenesis to the inhibitory effect of small increments in insulin concentrations, (2) gluconeogenesis could be suppressed by insulin but only at higher insulin concentrations, (3) this suppression of gluconeogenesis from alanine by insulin was due to an intrahepatic effect rather than an effect on the splanchnic extraction of alanine, and finally, (4) that insulin can suppress glucagon in the absence of hyperglycemia.     

Short-term treatment of alloxan-diabetic rats with intrajejunal administration of water-in-oil-in-water insulin emulsions.

Alloxan-diabetic rats with fasting blood glucose levels above 300 mg./100 ml. were treated with intrajejunal administration of water-in-oil-in-water (W/O/W) insulin emulsions via an indwelling catheter at a dose of either 25 or 50 U./100 gm. body weight, three times daily for five to fourteen days. The course of diabetes was followed by determinations of glucose levels in blood and urine. During treatment a significant reduction in urinary glucose levels was observed in all rats studied. In two rats treated with 25 U./100 gm., fasting blood glucose levels did not change significantly. In four of five rats treated with 50 U./100 gm., W/O/W insulin emulsions significantly lessened hyperglycemia during treatment. Quantitative estimates suggested that the effectiveness of 50 U./100 gm. of intrajejunal W/O/W insulin emulsions was comparable to that after intramuscular regular insulin at doses between 1 and 2 U./100 gm. These results would indicate that diabetes can be controlled by enteral administration of insulin preparations.     

Monozygotic triplets with discordance for diabetes mellitus and diabetic microangiopathy.

A set of monozygotic triplets (PE.K., P.K., S.K.) has been studied. There is no diabetes in first-degree relatives. PE.K. developed insulin-requiring (60 U. NPH) diabetes at the age of 13 years. Over a period of 11 years since that time, numerous studies of insulin and growth-hormone secretion were performed on P.K. and S.K., including multiple oral glucose tolerance tests (OGTTs), cortisone-primed oral glucose tolerance tests (C-OGTTs), intravenous glucose tolerance tests (IVGTTs), and intravenous tolbutamide tests (IVTTs). The results of each test were compared with age- and sex-matched control subjects. P. K. developed insulin-requiring (56 U. NPH) diabetes after remaining discordant for eight years. Glucose, insilin, and growth-hormone responses during all tests were normal except during the IVGTT performed four months prior to the onset of diabetes. This last IVGTT revealed a glucose disappearance rate of 0.98 per cent per minute, and the slope of the regression line of serum-insulin response (IRI) on blood glucose (BG) was markedly decreased to 0.005 micronU./ml. IRI/mg./dl. BG (controls 0.340 +/- 0.04; mean +/- S.E.M.). The insulin responses in P.K. and S.K. were similar during all OGTTs, C-OGTTs, and IVTTs. S.K. has continued to maintain normal glucose tolerance and normal insulin and growth-hormone responses during all tests. The histocompability antigen studies have revealed HLA-A2, AW24, BW15, and BW40 phenotype in these monozygotic triplets. Muscle capillary basement membranes of the nondiabetic triplet were normal, whereas both diabetic triplets manifested evidence of capillary basement membrane thickening. The clinical and biochemical profiles in these triplets and the capillary basement membrane data lend strong credence to the role of "nongenetic" determinants in the development of "genetic" diabetes as well as diabetic microangiopathy in juvenile-onset-type diabetes.