Absence of islet alpha cell function in pancreatectomized patients

Characterization of diabetes following pancreatic surgery in patients with congenital hyperinsulinism

Background

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycaemia in infancy that leads to unfavourable neurological outcome if not treated adequately. In patients with severe diffuse CHI it remains under discussion whether pancreatic surgery should be performed or intensive medical treatment with the acceptance of recurrent episodes of mild hypoglycaemia is justified. Near-total pancreatectomy is associated with high rates of insulin-dependent diabetes mellitus and exocrine pancreatic insufficiency. Little is known about the management and long-term glycaemic control of CHI patients with diabetes after pancreatic surgery. We searched the German/Austrian DPV database and compared the course of 42 CHI patients with diabetes to that of patients with type 1 diabetes mellitus (T1DM). Study groups were compared at diabetes onset and after a follow-up period of 6.1 [3.3–9.7] (median [interquartile range]) years.

Results

The majority of CHI patients with diabetes were treated with insulin (85.2% [70.9–99.5] at diabetes onset, and 90.5% [81.2–99.7] at follow-up). However, compared to patients with T1DM, significantly more patients in the CHI group with diabetes were treated with conventional insulin therapy (47.8% vs. 24.4%, p = 0.03 at diabetes onset, and 21.1% vs. 6.4% at follow-up, p = 0.003), and only a small number of CHI patients were treated with insulin pumps. Daily insulin dose was significantly lower in CHI patients with diabetes than in patients with T1DM, both at diabetes onset (0.3 [0.2–0.5] vs. 0.6 IE/kg/d [0.4–0.8], p = 0.003) and follow-up (0.8 [0.4–1.0] vs. 0.9 [0.7–1.0] IE/kg/d, p = 0.02), while daily carbohydrate intake was comparable in both groups. Within the first treatment year, HbA1c levels were significantly lower in CHI patients with diabetes (6.2% [5.5–7.9] vs. 7.2% [6.5–8.2], p = 0.003), but increased to a level comparable to that of T1DM patients at follow-up. Interestingly, in CHI patients, the risk of severe hypoglycaemia tends to be higher only at diabetes onset (14.8% vs. 5.8%, p = 0.1).

Conclusions

In surgically treated CHI patients insulin treatment needs to be intensified in order to achieve good glycaemic control. Our data furthermore emphasize the need for improved medical treatment options for patients with diazoxide- and/or octreotide-unresponsive CHI.

Odyssey between Scylla and Charybdis through storms of carbohydrate metabolism and diabetes: a career retrospective

This research perspective allows me to summarize some of my work completed over 50 years, and it is organized in seven sections. 1) The treatment of diabetes concentrates on the liver and/or the periphery. We quantified hormonal and metabolic interactions involved in physiology and the pathogenesis of diabetes by developing tracer methods to separate the effects of diabetes on both. We collaborated in the first tracer clinical studies on insulin resistance, hypertriglyceridemia, and the Cori cycle. 2) Diabetes reflects insulin deficiency and glucagon abundance. Extrapancreatic glucagon changed the prevailing dogma and permitted precise exploration of the roles of insulin and glucagon in physiology and diabetes. 3) We established the critical role of glucagon-insulin interaction and the control of glucose metabolism during moderate exercise and of catecholamines during strenuous exercise. Deficiencies of the release and effects of these hormones were quantified in diabetes. We also revealed how acute and chronic hyperglycemia affects the expression of GLUT2 gene and protein in diabetes. 4) We outlined molecular and physiological mechanisms whereby exercise training and repetitive neurogenic stress can prevent diabetes in ZDF rats. 5) We and others established that the indirect effect of insulin plays an important role in the regulation of glucose production in dogs. We confirmed this effect in humans and demonstrated that in type 2 diabetes it is mainly the indirect effect. 6) We indicated that the muscle and the liver protected against glucose changes. 7) We described molecular mechanisms responsible for increased HPA axis in diabetes and for the diminished responses of HPA axis, catecholamines, and glucagon to hypoglycemia. We proposed a new approach to decrease the threat of hypoglycemia.

Glucagon, in concert with insulin, supports the postabsorptive plasma glucose concentration in humans

OBJECTIVE

Given the interest in glucagon antagonism as a potential treatment of diabetes, we tested the hypothesis that glucagon, in concert with insulin, supports the postabsorptive plasma glucose concentration in humans.

RESEARCH DESIGN AND METHODS

Following preliminary studies that indicated that a peripheral intravenous insulin dose of 0.1 mU x kg(-1) x min(-1) (lower than those used previously) provides basal insulin replacement and that a glucagon dose of 1.0 ng x kg(-1) x min(-1) underreplaces basal glucagon, we infused the somatostatin analog octreotide (30 ng x kg(-1) x min(-1)) (with growth hormone replacement) over 4 h in 14 healthy adults on four separate occasions to produce endogenous insulin and glucagon deficiency with 1) saline (combined insulin and glucagon deficiency), 2) insulin replacement (isolated glucagon deficiency), 3) partial glucagon replacement (insulin and partial glucagon deficiency), and 4) insulin and partial glucagon replacement (partial glucagon deficiency).

RESULTS

During combined insulin and glucagon deficiency, glucose production decreased and then increased, and mean (+/-SE) plasma glucose decreased from 83 +/- 1 to 63 +/- 2 mg/dl at 60 min and then increased to 89 +/- 3 mg/dl at 240 min. During isolated glucagon deficiency, plasma glucose decreased to hypoglycemic levels and was 55 +/- 2 mg/dl at 240 min (P < 0.0001 vs. combined insulin and glucagon deficiency). Partial glucagon replacement raised plasma glucose to higher levels (P = 0.0469) during insulin deficiency and to higher levels (P = 0.0090) during insulin replacement.

CONCLUSIONS

These three findings provide direct evidence that glucagon, in concert with insulin, supports the postabsorptive plasma glucose concentration in humans.

Insulin receptors on circulating blood cells from patients with pancreatogenic diabetes: a comparison with type I diabetes and normal subjects

We studied 125I-insulin binding to erythrocytes from 14 patients with diabetes secondary to chronic pancreatitis or pancreatectomy and compared the results with those found in 10 patients with type I diabetes and 25 normal controls. Patients with pancreatogenic diabetes had higher 125I-insulin binding and enhanced tissue sensitivity to exogenous insulin measured with the glucose clamp technique as compared with patients with type I diabetes. Similar binding data were obtained with monocytes from 3 patients with pancreatogenic diabetes. The increase in insulin binding seemed due mainly to an increase in receptor number. The increase in insulin binding to cells from patients with pancreatogenic diabetes in comparison with cells from normal subjects was also seen in young-erythrocyte-rich fractions and in old-erythrocyte-rich fractions obtained from the mixed population of circulating erythrocytes by centrifugation in density gradient of Percoll-Pielografin. These data, in the absence of any sign of major hematological disorders, suggest that the increase in insulin receptors seen in erythrocytes and in monocytes from patients with pancreatogenic diabetes, can mirror a general phenomenon on tissues throughout the body, including major target cells for insulin and correlate with the heightened sensitivity to insulin characteristic of these patients. In conclusion, patients with pancreatogenic diabetes have increased insulin binding as compared to controls and to patients with type I diabetes with chronic hypoinsulinemia of the same degree. Thus, in addition to insulin deficiency, other factor (s), such as glucagon deficiency, are responsible for the clinical and metabolic differences between these two conditions of insulin deficiency.

Hyperglucagonemia and insulin-mediated glucose metabolism

The effect of chronic physiologic hyperglucagonemia on basal and insulin-mediated glucose metabolism was evaluated in normal subjects, using the euglycemic insulin clamp technique (+50, +100, and +500 microU/ml). After glucagon infusion fasting glucose increased from 76 +/- 4 to 93 +/- 2 mg/dl and hepatic glucose production (HGP) rose from 1.96 +/- 0.08 to 2.25 +/- 0.08 mg/kg X min (P less than 0.001). Basal glucose oxidation after glucagon increased (P less than 0.05) and correlated inversely with decreased free fatty acid concentrations (r = -0.94; P less than 0.01) and decreased lipid oxidation (r = -0.75; P less than 0.01). Suppression of HGP and stimulation of total glucose disposal were impaired at each insulin step after glucagon (P less than 0.05-0.01). The reduction in insulin-mediated glucose uptake was entirely due to diminished non-oxidative glucose utilization. Glucagon infusion also caused a decrease in basal lipid oxidation and an enhanced ability of insulin to inhibit lipid oxidation and augment lipid synthesis. These results suggest that hyperglucagonemia may contribute to the disturbances in glucose and lipid metabolism in some diabetic patients.

Insulin resistance is a prominent feature of patients with pancreatogenic diabetes

To compare in vivo insulin action in patients with diabetes secondary to pancreatic diseases (n = 9) to that in type I diabetic patients (n = 13) and in normal subjects (n = 8), we measured insulin-mediated glucose disposal by the euglycemic insulin clamp technique. Five of the nine patients with pancreatogenic diabetes had undergone total pancreatectomy. Similar plasma glucose (approximately 4.8 mmol/l) and insulin (approximately 70 mU/l) levels were maintained in all groups. The rate of glucose metabolism in the pancreatogenic diabetic patients (3.77 +/- 0.55 mg/kg/min) was 47% lower (P less than 0.001) than in normal subjects (7.05 +/- 0.57 mg/kg/min) and 21% lower (P less than 0.05) than in type I diabetic patients (5.54 +/- 0.39 mg/kg/min). The rates of glucose uptake were similarly reduced in totally pancreatectomized patients and in those with pancreatogenic diabetes due to other causes. During hyperinsulinemia induced by the clamp, glucose production (measured using 3-3H-glucose infusion) was completely suppressed in both the pancreatogenic diabetic patients and the normal subjects indicating that the impairment of in vivo insulin action was localized to the peripheral tissues. However, basal glucose production was elevated in the pancreatogenic diabetic patients (2.75 mg/kg/min, P less than 0.001) compared to the normal subjects (1.79 +/- 0.07 mg/kg/min). Glucose production rates were comparable in the totally pancreatectomized patients and in the other patients with pancreatogenic diabetes. The fasting plasma insulin level was, however, lower in the totally pancreatectomized (3.2 +/- 1.6 mU/L, P less than 0.05) than the other pancreatogenic (11.5 +/- 3.7 mU/L) diabetic patients. To examine the mechanisms of peripheral insulin resistance in the pancreatogenic diabetic patients, insulin binding and action were measured in isolated adipocytes. The pancreatogenic diabetic patients displayed normal insulin binding as well as normal rates of glucose transport and oxidation in adipocytes. In conclusion, patients with pancreatogenic diabetes demonstrated marked insulin resistance. Thus, impaired regulation of glucose production is a more likely explanation for the special clinical features of pancreatogenic diabetes than enhanced glucose utilization.

Hyperalaninaemia is an early feature of diabetes secondary to total pancreatectomy

High levels of gluconeogenic precursors have been reported in patients with long-term diabetes secondary to total pancreatectomy. In the present study, blood concentrations of alanine, lactate and pyruvate were measured in six patients undergoing total pancreatectomy and in nine control subjects undergoing major abdominal surgery. To exclude the simple effect of lack of insulin and hyperglycaemia in the development of hyperalaninaemia following total pancreatectomy, three pancreatectomized patients and five control subjects underwent surgical operation while connected to an artificial pancreas. Blood concentration of alanine was constant in the control subjects during surgery (182 +/- 20 and 243 +/- 31 mumol/l with and without the artificial pancreas, respectively). In pancreatectomized patients basal blood alanine levels were similar to those in control subjects. Blood alanine level rose quickly after removal of the pancreas from 182 +/- 24 to 285 +/- 15 mumol/1 (p less than 0.05) in the patients connected to the artificial pancreas, and from 198 +/- 17 to 395 +/- 47 mumol/1 (p less than 0.05) in patients undergoing total pancreatectomy without artificial pancreas. These values were higher than those observed in the control subjects at the end of the operation (192 +/- 22 and 230 +/- 45 mumol/l with and without artificial pancreas, respectively.) Basal and intraoperative blood concentrations of lactate and pyruvate were similar in pancreatectomized patients and control subjects.

Pancreatic glucagon secretion and exocrine function (BT-PABA test) in chronic pancreatitis

Plasma concentrations of pancreatic glucagon, C-peptide, and pancreatic polypeptide were measured during arginine stimulation in 16 patients with chronic pancreatitis, in eight subjects with idiopathic diabetes mellitus, and in seven healthy controls. The hormone responses were compared with exocrine pancreatic function as assessed using the urinary excretion rate of p-aminobenzoic acid after oral ingestion of n-benzoyl-l-tyrosyl-p-aminobenzoic acid (BT-PABA). The increase in pancreatic glucagon levels during arginine stimulation was significantly reduced in patients with chronic pancreatitis compared to healthy controls, most markedly in those with secondary diabetes. In contrast, the glucagon response was unimpaired in patients with idiopathic diabetes. The arginine-induced increase in plasma glucagon and C-peptide concentrations correlated significantly with urinary PABA excretion in chronic pancreatitis (P less than 0.001, P less than 0.01, respectively). The responses of plasma C-peptide and pancreatic polypeptide separated pancreatitic and idiopathic diabetes less well. Thus, the glucagon response to arginine distinguished secondary diabetes due to chronic pancreatitis and idiopathic diabetes mellitus. The correlation between urinary PABA excretion and glucagon levels suggests that in chronic pancreatitis there is a parallel impairment of exocrine and endocrine function.

C-peptide measurement: methods and clinical utility

Proinsulin is the single chain precursor of insulin. It consists of insulin, plus a peptide which connects the A and B chains of insulin. This peptide is termed C-peptide. C-peptide an insulin are secreted in equimolar amounts from pancreatic beta-cells, Hence, circulating C-peptide levels provide a measure of beta-cell secretory activity. C-peptide measurements are preferable to insulin measurements because of lack of hepatic extraction, slower metabolic clearance rate, and lack of cross reactivity with antibodies to insulin. This article reviews the methods for determination of C-peptide levels in body fluids, and discusses the applications of C-peptide measurement. These include the investigation of hypoglycemia and the assessment of insulin secretory function in insulin-treated and non-insulin-dependent diabetics. The contribution of C-peptide measurement to the understanding of the interrelationships between insulin secretory function and age, sex, obesity, blood lipids, and blood glucose concentrations will also be evaluated.

Circulating glucagon after total pancreatectomy in man

In five totally pancreatectomized human subjects the secretion of gut-derived glucagons was stimulated by ingestion of a meal rich in fat and carbohydrates. Glucagon-like immunoreactivity in plasma, measured with an antiserum against the 6-15 sequence, increased fivefold in response to the meal. Glucagon like immunoreactivity measured with a antiserum against the C-terminal sequence was initially normal (12-13 pmol/l), increased slightly (to 20 pmol/l), and then decreased (to approximately 6 pmol/l). The chromatographic profile of glucagon-like immunoreactivity in plasma at maximum stimulation was studied after concentration by affinity chromatography. Both assay systems identified two peaks (at Kd-values of 0.30 and 0.60-0.65, and 0.30 and 0.70, respectively). The position at Kd 0.70 corresponds to that of glucagon 1-29. The same components may be identified in plasma from normal subjects. It is concluded that the human intestine is capable of generating all of the molecular forms of glucagon which normally are present in plasma.

Effect of insulin replacement on intermediary metabolism in diabetes secondary to pancreatectomy

Patients with diabetes due to pancreatectomy have metabolic features different from Type 1 (insulin-dependent) diabetes after insulin withdrawal. Whether or not glucagon by itself or combined glucagon-insulin absence are responsible for this metabolic behaviour is unknown. This study was carried out to evaluate the ability of insulin replacement to abolish differences between patients with Type 1 diabetes and patients with diabetes due to pancreatectomy. We studied the diurnal patterns of intermediary metabolites, free insulin, and glucagon using the Biostator (glucose-controlled insulin infusion system) and intensive subcutaneous insulin therapy in five patients after total pancreatectomy, five after partial pancreatectomy and seven patients with Type 1 diabetes. All were studied for 24 h after an overnight period of normoglycaemia. Insulin requirement was lower in the patients with total pancreatectomy than in patients with partial pancreatectomy or Type 1 diabetes during both types of insulin treatment (p less than 0.05). Blood glucose and free insulin were similar in all the groups in both conditions. Immunoreactive glucagon was higher in the patients with diabetes secondary to pancreatectomy than in Type 1 diabetic patients. However, glucagon levels did not increase after arginine infusion in the patients with total pancreatectomy, and column chromatography of blood samples from two totally pancreatectomized patients showed no significant levels of immunoreactive pancreatic glucagon. Non-esterified fatty acids and ketone bodies were similar during Biostator and intensive subcutaneous insulin therapy. By contrast, gluconeogenic precursors (lactate, pyruvate, alanine and glycerol) were higher in patients with total pancreatectomy than in patients with partial pancreatectomy and Type 1 diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Study of A- and B-cell function in beta-thalassemia major

Hepatic and pancreatic damage owing to iron overload is often present in patients with beta-thalassemia major. In order to investigate B-cell function and hepatic insulin clearance in these patients, under a high transfusion program and regular chelation therapy, we studied the glucose (BG), insulin (IRI) and C-peptide (CPR) response and the CPR/IRI ratio after OGTT in 27 patients with Cooley's anemia and in 10 sex- age- and weight-matched healthy subjects; we also studied BG and IRI levels after IVGTT in 9 beta-thalassemic patients and in 9 control subjects. Furthermore, BG, CPR, IRI and glucagon (IRG) response to arginine infusion were evaluated in 5 thalassemic patients with normal OGTT and in 5 age-, sex- and weight-matched normal children, in order to assess pancreatic A-cell function, too. OGTT and IVGTT were normal in the patients with beta-thalassemia major. Plasma IRI level 30 min after an oral glucose load and the insulinogenic index for cumulative intervals were significantly lower in thalassemics after OGTT, whereas the insulin response and insulinogenic index were normal following i.v. glucose. No significant difference was observed for the CPR/IRI ratio during OGTT between thalassemics and normal subjects. Finally, BG, CPR, IRI and IRG levels were similar in the thalassemic patients and in healthy children both fasting and following arginine infusion. Our data suggest that patients with beta-thalassemia major, under a high transfusion program and regular chelation therapy, may have normal glucose tolerance and normal hepatic insulin clearance in spite of iron overload in pancreas and liver. Insulin response to oral glucose was lower than the one to IVGTT, probably because of diminished secretion of the gastrointestinal hormones which stimulate insulin release.