Effect of the enteroinsular axis on both the A- and B-cell response to arginine after oral glucose in man

Summary Studies were made on the effect of the enteroinsular axis on amino acid-induced insulin and glucagon secretion during hyperglycaemia in man. The responses of plasma immunoreactive insulin, C-peptide, and immunoreactive glucagon to arginine infusion were investigated in nine healthy subjects after induction of hyperglycaemia by an oral glucose load and by intravenous glucose infusion to produce similar glucose concentrations in the arterialised blood. The plasma immunoreactive insulin and C-peptide levels increased to higher levels after an oral glucose load than after an intravenous infusion of glucose. The incremental areas under the immunoreactive insulin and C-peptide curves during arginine infusion were significantly greater (p<0.01) after oral than after intravenous glucose administration. The plasma immunoreactive glucagon level was suppressed equally after oral and intravenous glucose loads. However, during subsequent arginine infusion, the plasma immunoreactive glucagon level rose more in the presence of hyperglycaemia induced by oral than intravenous glucose. The incremental area under the plasma immunoreactive glucagon curve during arginine infusion was 1.6-fold greater after glucose ingestion than after intravenous glucose infusion. These results suggest that the enteroinsular axis has a stimulatory effect on the responses of pancreatic A and B cells to arginine after oral glucose administration.     

Basal and glucose- and arginine-stimulated serum concentrations of insulin, C-peptide, and glucagon in hyperthyroid patients

The effect of oral glucose and arginine infusion on plasma glucose, glucagon, serum insulin, and C-peptide concentrations was evaluated in 16 patients with hyperthyroid Graves' disease and in ten euthyroid age- and sex-matched normal subjects. Basal plasma glucose concentrations were significantly higher in the hyperthyroid patients, but the plasma glucose response following glucose and arginine administration was similar in the two groups. The insulin response was similar in the hyperthyroid and normal subjects after glucose administration and significantly lower during arginine infusion in the hyperthyroid patients. The serum C-peptide response to both glucose and arginine administration was markedly blunted in the hyperthyroid patients, and the plasma glucagon response to arginine infusion was decreased. These results suggest that pancreatic beta and alpha cell secretory function is impaired in hyperthyroidism as assessed by C-peptide and glucagon secretion following oral glucose administration and arginine infusion. The apparent discrepancy between C-peptide and insulin secretion in the hyperthyroid patients following glucose administration might be due to diminished hepatic extraction of insulin or enhanced metabolism of C-peptide.     

Lack of effect of high-dose biosynthetic human C-peptide on pancreatic hormone release in normal subjects

We studied the effect of high doses of biosynthetic human C-peptide on pancreatic hormone secretion in response to oral (75 g) and intravenous [( IV] 0.33 g/kg of D50%) glucose on normal volunteers. The infusion of human C-peptide at a rate of 360 ng/kg/min body weight, increased the plasma C-peptide concentration from a basal level of 0.32 +/- 0.04 pmol/mL to 38.5 +/- 1.8 pmol/ml. Overall, C-peptide had no significant effect on the serum levels of glucose, insulin, proinsulin, glucagon, and pancreatic polypeptide, either under basal conditions or following IV and oral glucose administration. However, small decreases in glucose and insulin concentrations that were not statistically significant were seen during the first hour after C-peptide infusion. The results of the present studies are therefore consistent with the conclusion that even supraphysiologic plasma concentrations of infused C-peptide do not affect basal insulin secretion or overall insulin secretory responses to oral or IV glucose. However, we cannot definitively exclude a small reduction in insulin secretion in the first hour after oral glucose ingestion.     

The effect of various blood glucose levels on post-glucagon C-peptide secretion in type 2 (non insulin-dependent) diabetes.

We investigated how different plasma glucose concentrations could significantly modify the C-peptide response to glucagon. Twenty poorly-controlled (HbA1c 10.2 +/- 1.5%) non insulin-dependent (NIDDM) subjects (body mass index 27 +/- 1.8), 2 treated with diet alone and 18 with oral hypoglycemic agents were studied. The first day glucagon (1 mg iv) was injected, patients being fasting and untreated. Mean plasma glucose levels were 11.4 +/- 1.2 mM. On a second non consecutive day, after an overnight fast, the same patients were connected to a closed-loop insulin infusion system (Betalike, Genoa), their blood glucose concentrations were stabilized within a normoglycemic range (5-5.5 mM) for 2 h and insulin infusion was stopped. The glucagon test was repeated 30 min later. Blood samples were taken 0, 6, 10, 20 min after glucagon injection. In the second test, basal, and 6, 10 and 20 min post-glucagon glucose levels were significantly lower (p less than 0.001); similarly C-peptide concentrations were significantly reduced both in basal conditions (0.55 +/- 0.04 vs 0.37 +/- 0.04 nM; p less than 0.001) and 6 (0.92 +/- 0.06 vs 0.6 +/- 0.06; p less than 0.001), 10 (0.79 +/- 0.06 vs 0.56 +/- 0.06; p less than 0.001) and 20 min (0.64 +/- 0.05 vs 0.44 +/- 0.04; p less than 0.001) after stimulation. The C-peptide secretion area showed the same trend (49.5 +/- 4.8 vs 32.1 +/- 5.8; p less than 0.001). In conclusion, our data confirms that blood glucose levels modulate the pancreatic insulin secretion; glycemic normalization significantly reduced both basal and post-glucagon C-peptide release.     

Hyperinsulinaemia in non-cirrhotic haemochromatosis: impaired hepatic insulin degradation?

Summary This study investigated early alterations of glucose metabolism in idiopathic haemochromatosis. Circulating concentrations of glucose, insulin, C-peptide, glucagon, and gastric inhibitory polypeptide (GIF) were measured after a 100-g oral glucose load in 10 men with idiopathic haemochromatosis in the non-cirrhotic stage of the disease. All had normal glucose tolerance and normal body weight. Ten matched healthy subjects were studied as controls. Insulin concentrations increased to significantly higher levels in patients with idiopathic haemochromatosis than in the control subjects from 30 to 180min after the glucose load (p<0.01), while fasting insulin concentrations were not significantly different (p> 0.05). Concentrations of glucose, glucagon, C-peptide, and GIF were not significantly different at any time (p> 0.05). Thus, patients with idiopathic haemochromatosis show hyperinsulinaemia and hence insulin resistance without impaired glucose tolerance in the non-cirrhotic stage. Since pancreatic insulin secretion (C-peptide), glucagon secretion, and the entero-insulinar axis (GIP) are not impaired in these non-cirrhotic patients with idiopathic haemochromatosis, iron accumulation in the hepatocytes may be responsible for the impaired insulin effect and may cause impaired hepatic insulin extraction.     

Endocrine pancreatic secretion in patients after acute pancreatitis

In 14 nonobese patients after acute pancreatitis and with normal oral glucose tolerance, the response of insulin, C-peptide, and pancreatic glucagon after 100 g of oral glucose was assessed. The curves of insulin and C-peptide were significantly raised compared with those of controls, and no difference was found between the response of patients with a negative (n = 8) and a positive (n = 6) family history of type II diabetes. The curves of pancreatic glucagon did not differ from those found in controls. Our results indicate that a normal response to glucose after recovery from an attack of acute pancreatitis is maintained at the cost of increased insulin secretion.     

Secretion and hepatic extraction of insulin after weight loss in obese noninsulin-dependent diabetes mellitus

We assessed the effects of weight loss on pancreatic secretion and hepatic extraction of insulin in 11 obese subjects with noninsulin-dependent diabetes mellitus. Weight loss of 15.4 +/- 2.0 kg (mean +/- SE) resulted in decreased fasting insulin [20.2 +/- 2.5 to 9.8 +/- 2.5 microU/mL (145 +/- 18 to 70 +/- 18 pmol/L); P less than 0.02] and C-peptide (850 +/- 80 to 630 +/- 110 pmol/L; P less than 0.05) levels. The plasma glucose response to oral glucose and iv glucagon was improved with unchanged peripheral insulin levels. When plasma glucose levels were matched to those before weight loss, peripheral serum insulin and plasma C-peptide responses to iv glucagon were increased and similar to those in obese nondiabetic subjects studied at euglycemia. The total insulin response (area under the curve) to iv glucagon was reduced 30% (P less than 0.005), while the total C-peptide response area did not change after weight loss. At matched hyperglycemia, the total response area was enhanced 72% for insulin (P less than 0.002) and 64% for C-peptide (P less than 0.001). Incremental (above basal) response areas after weight loss did not change for insulin, but increased 66% for C-peptide (P less than 0.05). The incremental areas were augmented nearly 2-fold (196%) for insulin (P less than 0.01) and 1.7-fold (173%) for C-peptide (P less than 0.01) when assessed at matched hyperglycemia. Both basal (7.3 +/- 0.5 to 14.1 +/- 1.8; P less than 0.01) and total stimulated (6.1 +/- 0.4 to 8.8 +/- 1.4; P less than 0.05) C-peptide to insulin molar ratios increased after weight loss. We conclude that after weight loss in noninsulin-dependent diabetes mellitus, 1) insulin secretion is decreased in the basal state but increased after stimulation; 2) changes in insulin secretion are reflected by peripheral levels of C-peptide but not insulin, due in part to enhanced hepatic insulin extraction; and 3) at matched levels of hyperglycemia insulin secretion is markedly increased and similar to that in obese nondiabetic subjects studied at euglycemia.     

Improved beta-cell function after intensive insulin treatment in severe non-insulin-dependent diabetes

In Type II, non-insulin-dependent diabetes, insulin secretion is often reduced to the point where oral hypoglycaemic agents fail to control the plasma glucose level. We studied 12 patients (age 41-66 years; 4 lean, 8 obese) with Type II diabetes mellitus for 1-25 years who were uncontrolled despite maximal dose glibenclamide and metformin. After withdrawal of medication, blood glucose control was determined by measuring glucose before and 2 h after each meal for 48 h, and beta-cell function by insulin or C-peptide response to glucagon and to iv glucose. Following these tests, intensive insulin treatment (CSII) was initiated, and near-euglycaemia (mean of 7 daily glucose determinations less than 7.7 mmol/l) was maintained for 16.6 +/- 1.5 days, at which time the tests were repeated. Mean daily insulin requirement was 61 +/- 9 IU (0.81 +/- 0.09 IU/kg). Glucose control was improved after cessation of CSII (mean glucose 12.7 +/- 0.6 mmol/l after vs 20 +/- 1.5 mmol/l before, P less than 0.005). Maximum incremental C-peptide response improved both to glucagon (214 +/- 32 after vs 134 +/- 48 pmol/l before, P = 0.05) and to glucose iv bolus injection (284 +/- 53 vs 113 +/- 32 pmol/l, P less than 0.05). Peak insulin response, measured after iv glucose infusion, also tended to be higher in the post-CSII test (42 +/- 18 vs 22 +/- 5.6 mU/l). Basal and stimulated proinsulin concentrations were high relative to C-peptide levels during the pre-treatment period, but returned to normal after CSII.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circulating somatostatin after oral glucose in hypothyroidism

The response of circulating somatostatin-like immunoactivity (SLI) to oral glucose and its relation to other pancreatic islet cell hormones were studied in 10 hypothyroid subjects before and after treatment. None of the patients suffered from diabetes mellitus or obesity. Compared with normal controls, the hypothyroid subjects had higher fasting and stimulated SLI levels but lower fasting pancreatic glucagon levels. Integrated glucose and insulin responses following glucose ingestion were normal, but the peak insulin response was delayed to 120 min suggesting impaired pancreatic beta-cell response to oral glucose. On the other hand, the peak response of plasma C-peptide was higher probably because of a reduction in metabolic clearance. In both hypothyroid subjects and controls, a significant correlation was found between the maximal increment of SLI and the maximal decrement of glucagon following oral glucose. In conclusion, plasma SLI is increased in hypothyroidism. The changes in SLI may be due to either an increased hormonal secretion or a reduced metabolic clearance in hypothyroidism. This elevated SLI might contribute to the slower gastrointestinal motility observed in hypothyroidism. Our data also suggest that the reduction in glucagon secretion may be secondary to the increase in circulating SLI.     

Starvation enhances the ability of insulin to inhibit its own secretion

To examine whether decreased insulin secretion during starvation is related to a change in the ability of insulin to inhibit its own secretion, plasma C-peptide was measured after plasma insulin levels were acutely raised by intravenous (IV) insulin infusion in a dose of 40 and 80 mU/M2/min in obese subjects before and after a 72 hour fast. Plasma glucose concentration was maintained +/- 4% of basal levels by a variable glucose infusion. During the 80 mU infusion, at plasma insulin levels of 200 microU/mL, plasma C-peptide fell by 0.17 pmol/mL in the fed state. In the fasted state, despite basal levels that were 36% lower, C-peptide decreased by 0.21 pmol/mL. Highly significant increases in percent suppression after fasting were noted during both 40 mU and 80 mU studies. The plasma C-peptide response was related to the insulin infusion dose in both the fed and fasted state. In contrast, alpha cell suppression by insulin, as determined by plasma glucagon levels, was not altered by fasting. It is concluded that enhanced inhibitory influences of insulin on the beta cell during starvation may be a physiologically important mechanism for diminished insulin secretion during the transition from the fed to the fasting state.     

Effect of pancreas transplantation on glucose counterregulation in insulin-dependent diabetic patients prone to severe hypoglycaemia.

Pancreatic transplantation was performed in three patients with insulin-dependent diabetes mellitus in whom recurrent and severe episodes of hypoglycaemia had been found to be due to defective glucose counterregulation. Thus in these patients the spontaneous blood glucose recovery after insulin-induced hypoglycaemia (0.1 U kg-1 h-1 i.v. insulin until blood glucose levels fell below 2.8 mmol l-1) was delayed, and the responses of glucagon, epinephrine and growth hormone (GH) were absent or diminished. After pancreas transplantation the patients exhibited essentially normal blood glucose control. When the insulin infusion test was repeated 3 months after the transplantation, the blood glucose level recovered rapidly after insulin withdrawal. The glucagon response was restored, and the responses of epinephrine and GH were improved. Plasma C-peptide was suppressed by approximately 50%, which is less than is observed in normal subjects. It is concluded that glucose counterregulation improves after pancreas transplantation. This appears to be mainly due to an improvement in the hypoglycaemia-induced glucagon response, but an amelioration of sympatho-adrenal and hypothalamic-pituitary regulatory mechanisms may also be involved. The apparent failure to suppress completely the insulin release from the denervated pancreas transplant indicates that inhibition of beta-cell secretion during insulin-induced hypoglycaemia may be partly under neural control.     

Somatostatin effect in postprandial hypoglycemia

The effect of the administration of oral glucose with or without a simultaneous intravenous somatostatin infusion on blood glucose, immunoreactive insulin, C-peptide, and glucagon levels in seven patients with idiopathic postprandial hypoglycemia was studied. Oral glucose alone induced an excessive insulin response and hypoglycemia, whereas a slight suppression in glucagon levels without any increase at the hypoglycemic nadir was observed. The simultaneous administration of somatostatin significantly reduced the insulin response and induced a slower rise of blood glucose; no hypoglycemia developed. Only minor variations in glucagon were observed with respect to the basal test. A rebound in insulin, C-peptide, and glucagon levels was observed at the end of the somatostatin infusion. These data show that somatostatin can suppress glucose-induced hypoglycemia in these subjects, thus suggesting that its long-acting analogues might be worth a therapeutic trial in severe idiopathic postprandial hypoglycemia.     

Peripheral hyperinsulinemia of simple obesity: pancreatic hypersecretion or impaired insulin metabolism?

Insulin and C-peptide levels in peripheral blood in the fasting state and after an oral glucose load were measured in 65 nondiabetic, obese subjects and 65 age- and sex-matched nondiabetic normal weight subjects. Fasting insulin and C-peptide levels were significantly higher in obese than in nonobese subjects, whereas 1 and 2 h after the oral glucose load only insulin concentrations were significantly higher in the obese subjects. C-peptide to insulin molar ratios, as well as the relation between the incremental areas of the two peptides, were used as relative measures of hepatic insulin extraction. In the fasting state the ratios between C-peptide and insulin were similar in obese and nonobese subjects, whereas after glucose they were significantly lower in the obese individuals. Similarly, the relations between C-peptide and insulin incremental areas were significantly lower in obese than in nonobese subjects. The comparison of the corresponding plasma levels and areas of C-peptide and insulin after glucose showed that for the same C-peptide value, the insulin value was higher in the obese group. Last, in obese subjects the parameter used as an estimate of hepatic removal of insulin after oral glucose inversely correlated with the fasting insulin concentration and the insulin incremental area after glucose. These results suggest that in obesity peripheral hyperinsulinemia depends on pancreatic hypersecretion of insulin in the fasting state and impaired hepatic insulin metabolism after oral glucose loading.     

Short time effects of growth hormone on glucose metabolism and insulin and glucagon secretion in normal man.

The present study was undertaken in order to evaluate the acute metabolic and hormonal effects of human growth hormone in healthy subjects. Glucose turnover, plasma glucose, FFA, insulin, C-peptide, glucagon, and somatostatin concentrations were determined in the fasting state after a bolus injection of placebo or growth hormone in quantities producing increases in plasma growth hormone levels within the normal physiological range. We found that growth hormone administration resulted in negligible changes in plasma glucose, no significant changes in appearance or disappearance rates of glucose, a moderate increase in FFA and a moderate fall in plasma insulin, C-peptide and glucagon concentrations, while plasma somatostatin levels were unchanged. These findings suggest that rapid changes in plasma growth hormone concentrations, corresponding to the fluctuations seen during normal daily life, may play a role in the short time regulation of blood glucose concentration through an inhibition of insulin and glucagon secretion.     

Infusion of synthetic human C-peptide does not affect plasma glucose, serum insulin, or plasma glucagon in healthy subjects

We studied six healthy male subjects to determine whether a four-hour infusion of synthetic human C-peptide sufficient to achieve mean (+/- SD) peripheral plasma concentrations of 1.3 +/- 0.7 pmol/mL affected plasma glucose, serum insulin, or plasma glucagon. Subjects were studied in a fasting state and following an oral glucose load during four-hour 0.9% NaCl (control) and C-peptide (mean dose: 70 nmol) infusions. No differences were observed between saline and C-peptide infusions for mean values of fasting plasma glucose (94 +/- 6 v 87 +/- 5 mg/dL), serum insulin (3 +/- 1 v 2 +/- 1 microU/mL), or plasma glucagon (124 +/- 65 v 112 +/- 70 pg/dL). Following oral glucose ingestion no differences were detected between saline and C-peptide infusions for mean peak values of plasma glucose (168 +/- 18 v 168 +/- 31) and serum insulin (59 +/- 6 v 57 +/- 21) or mean nadir values of plasma glucagon (80 +/- 73 v 75 +/- 70). There was a slight delay in the insulin rise following oral glucose on the C-peptide infusion day, but differences between mean values for individual sampling times were not statistically significantly different.     

The effect of acetylsalicylic acid on plasma glucose and the response of glucose regulatory hormones to intravenous glucose and arginine in insulin treated diabetics and normal subjects

The effects of oral acetylsalicylic acid (ASA) 3.2 g a day for 5 days on glucose and glucose regulatory hormones were examined in 4 normal subjects, and in 14 insulin requiring diabetic subjects, 9 of whom had significant residual Beta cell function as assessed by C-peptide secretion and 5 of whom did not. In all subjects plasma samples were assayed for glucose, C-peptide, glucagon, growth hormone, and cortisol during sequential intravenous glucose and arginine infusions while the subject was receiving ASA or placebo. The plasma samples from the normal subjects were assayed for insulin.ASA significantly increased early insulin release (p < 0.02) and decreased plasma glucose (p < 0.02) in response to intravenous glucose in the normal subjects. ASA had no effect on glucose or hormone responses to intravenous arginine.The C-peptide positive diabetics had a significantly lower basal plasma glucose while receiving ASA, and this difference persisted throughout the test (p < 0.02). C-peptide levels were similar to control during ASA ingestion. ASA had no significant effect on plasma glucose in the C-peptide negative diabetics.ASA significantly increased fasting plasma glucagon in the normal subjects (p < 0.05) and C-peptide negative diabetics (p < 0.05). There was a significant positive correlation between the changes in plasma glucose and plasma glucagon both basally and 10 min after the commencement of the glucose infusion for the C-peptide negative diabetics but not for the C-peptide positive diabetics or the normal subjects. ASA had no effect on plasma growth hormone or cortisol levels.The reduction of plasma glucose by ASA in man is dependent on continuing β cell function. In the absence of β cell function the stimulatory effect of ASA on glucagon production becomes the major determinant of ASA's effect on plasma glucose. The effects of ASA on pancreatic islet function appears to be the major determinant of its effect on glucose handling.     

Glucagon-stimulated insulin secretion in patients with type 2 diabetes mellitus: support for the concept of glucose toxicity.

Parameters of blood glucose control and insulin secretion were evaluated in 114 patients with type 2 diabetes mellitus, who were no longer controlled satisfactorily by maximal doses of oral hypoglycaemic agents, and compared with those obtained in 11 healthy control subjects, 32 patients with recently-diagnosed type 2 diabetes, and 16 tablet-treated and 36 insulin-treated patients. Newly-diagnosed patients were slightly younger (60 +/- 13 yr) and had a slightly higher body mass index (29.4 +/- 6.5 kg/m2). Known duration of diabetes was 9 yr (range 1-37) in secondary failure, and 11 yr (range 1-31) in insulin-treated patients. Fasting blood glucose was the highest (13.8 +/- 2.8 mmol/l) in secondary failure and newly-diagnosed patients (12.6 +/- 3.8 mmol/l) compared to tablet-treated (8.7 +/- 3.3 mmol/l) and insulin-treated patients (9.6 +/- 3.2 mmol/l, p less than 0.05). HbA1c levels were comparably elevated. In insulin-treated patients, fasting plasma C-peptide levels were lower relative to the mutually comparable levels in the other 3 diabetic groups. Fasting plasma insulin levels did not differ between the 4 diabetic groups. C-peptide release after glucagon (C-peptide AUC) was comparable in all 4 diabetic groups, although in tablet-treated patients the ratio C-peptide AUC/fasting blood glucose was higher (p less than 0.05). We conclude that the clinical usefulness of determining residual insulin secretion in type 2 diabetic patients is limited, and that the similar reduction of insulin secretion in severely hyperglycaemic newly-diagnosed and secondary failure type 2 diabetic patients supports the concept of "glucose toxicity".     

Reduced insulin secretion by subtotal pancreatectomy: preservation of insulin sensitivity and glucose tolerance in postoperative patients

This study investigated insulin sensitivity and glucose tolerance after subtotal pancreatectomy for carcinoma of the head of the pancreas. Twelve consecutive, non-diabetic patients were studied after potentially curative surgery at which the distal pancreas was stapled off, leaving approximately 15% of the pancreas in situ. Brief infusions of insulin (10 mU kg-1) and glucose (25 g) were given before and 4 days after operation. Postoperatively, blood glucose levels remained unchanged, whereas fasting levels of insulin. C-peptide, and pancreatic glucagon were decreased, although significantly (p less than 0.01) only for glucagon. The early and late phases of the insulin and C-peptide responses to glucose were severely reduced. Notably, the hypoglycemic action of insulin and the glucose tolerance were similar to those observed before operation. It is concluded that an acute reduction in pancreatic mass does not impair insulin action or glucose tolerance shortly after surgery. This contrasts with the insulin resistance and glucose intolerance seen shortly after pancreas-preserving intra-abdominal procedures of similar size. It is suggested that the decrease in glucagon levels is at least partly responsible for the preservation of insulin action after subtotal pancreatectomy.     

C-peptide reserve in insulin-dependent diabetes

Summary Residual beta cell secretory capacity was assessed in short term (2 months to 2 years) and long term (5 to 8 years) insulin-dependent diabetics by measurement of serum C-peptide immunoreactivity during three provocative tests: glucose, tolbutamide, and glucagon. Minimal C-peptide secretion could be detected in only one out of seven long term diabetics by the stimulatory tests. All seven short-term diabetics responded to at least one provocative test of beta cell reserve, although these responses were blunted. The greatest C-peptide responses occurred after glucagon administration (mean increase 0.62 pmol/ml) in short-term responders. Patients who responded to one test did not necessarily respond to another stimulus. There was no correlation between basal C-peptide levels and the ability to provoke further C-peptide secretion by any of the three tests. C-peptide responses did not correlate with % Haemoglobin A_1c, mean fasting blood glucose levels, or mean blood glucose concentrations during an oral glucose tolerance test. The data indicate that stimulation tests are only useful in assessing endogenous beta cell reserve in patients with diabetes of less than 5 years duration. In diabetics of longer duration there is little insulin reserve above basal levels.     

Pancreatic beta-cell secretion after oral glucose and intravenous glucagon: different responses to dietary control of plasma glucose in newly diagnosed patients with NIDDM

Pancreatic beta-cell secretion after oral glucose or intravenous glucagon stimulation was studied in newly diagnosed patients with non-insulin-dependent diabetes mellitus (NIDDM) before and after glycemic control by diet treatment alone. Insulin secretion to oral glucose showed significant improvement, while C-peptide release by glucagon showed no significant difference before and after diet treatment. The finding suggests that pancreatic beta-cell response to oral glucose varies with different metabolic states, but this is not so after glucagon stimulation in NIDDM patients.