Plasma Insulin Values Research Articles

The effect of a high-carbohydrate diet on glucose, insulin sensitivity and plasma insulin in rats.

SUMMARY When groups of rats were kept on control and high-carbohydrate diets from the end of lactation until their body weight reached 150 g. it was found that the animals fed on the high-carbohydrate diet gained weight more rapidly, with an increase in fat deposits. Glucose and plasma insulin in both groups were compared with the amounts of hormone extracted from their pancreases. When the rats on the control diet were killed the insulin and glucose plasma levels were 40 ± 3 μu./ml. and 156·69 ± 13 mg./100 ml. respectively. After 17–20 hr. fasting these values decreased significantly (P < 0·01) to 18 ± 1·5 μu./ml. and 116 ± 13 mg./ml. The amount of insulin in the pancreas was not modified by fasting. In the rats fed on the high-carbohydrate diet the plasma insulin and glucose values were higher than those in the control rats (50 ± 3·8 μu./ml. and 187 ± 19 mg./100 ml.); after 17–20 hr. starvation the glucose levels were reduced and the plasma insulin concentration remained higher (44 ± 2·9 μu./ml.); the insulin content of the pancreas was higher than in the control rats. In vitro the epididymal fat and the diaphragm of the rats on the high-carbohydrate diet were less sensitive to insulin than the same tissues in the controls.

Relationship between obesity, chemical diabetes and beta pancreatic function in children.

Seventy-nine children, aged two and one-half to thirteen years, divided into four groups on the basis of their weight and family history of diabetes mellitus (one sibling or one parent with insulin dependent diabetes), were examined. The data showed that the occurrence of chemical diabetes was higher in children with family history of diabetes. In obese children hyperinsulinism was present, but glucose intolerance was associated with impairment of insulin secretion. The findings suggest that there probably is a genetically predisposed incapacity of beta cells to respond to various stimuli, and diabetes may develop in the face of relative insulin deficiency, regardless of the, absolute value of plasma insulin.

Pitfalls in Interpretation of Oral Glucose Tolerance Tests in the Newborn

In the course of study of metabolic responses to oral glucose in eleven newborn infants of gestational diabetic mothers (IGDM), three infants had significantly higher blood glucose and plasma insulin values than those of the other eight. The only difference between the two groups was that, in the former, blood was obtained from an umbilical vein catheter and, in the latter, from a peripheral vein. In order to determine if the differences observed in insulin and glucose values were due to sampling sites, standard oral glucose tolerance tests were done with simultaneous sampling from both sources. Material and Methods Two-hour oral glucose tolerance tests (2 gm per kilogram) were done in five IGDM.

Dissappearance rate of exogenous insulin, insulin sensitivity, responses of plasma growth hormone and cortisol and urinary epinephrine to hypoglycemia in prediabetic subjects.

Insulin sensitivity was found to be increased in a group of nine prediabetic subjects, indicating that some mechanism(s) compensates for the decreased ability to secrete insulin in response to glucose. Diabetes probably develops in prediabetic subjects when such a compensation is lost. The disappearance rate of insulin was of identical magnitude in the prediabetic and normal groups, indicating that the lower plasma insulin values in prediabetes do reflect a decreased secretion of insulin. No difference was found between the two groups regarding the responses of HGH, Cortisol and epinephrine to hypoglycemia.

Diminished glucose tolerance and immunoreactive insulin response in patients with nonischemic cardiac disease.

Intravenous infusion of glucose in patients with compensated nonischemic cardiovascular disease has demonstrated that the glucose disappearance slope, G K , is significantly lower than in normal subjects. Immunoassay of plasma insulin in 13 of these cardiac patients showed a reduced insulin response to hyperglycemia in the majority. All had a delayed decline of plasma insulin values. Plasma free fatty acids (FFA) were significantly elevated in the fasting state but were not significantly correlated with the reduced G K . During the acute hyperglycemia, plasma free fatty acid, potassium, and inorganic phosphate concentrations declined as in the normal subjects. Although cardiac index was reduced in most patients, a linear correlation with G K was not obtained. To examine the possible role of enhanced sympathetic stimulation seen in cardiac patients, norepinephrine was infused into normal subjects during a glucose-tolerance test (GTT). A decline in glucose tolerance and plasma insulin was observed to levels approximating those seen in the cardiac patients, suggesting a neurohumoral mechanism for the glucose intolerance in cardiac patients. It would therefore appear that the glucose intolerance in compensated cardiac subjects with a reduced cardiac output is frequently an acquired rather than a genetically determined metabolic disorder.

Metabolic studies in diabetics on tolbutamide. Comparison of a single dose with a divided dose regimen.

This study compares blood glucose, plasma insulin and tolbutamide values throughout 48 h in 10 subjects on a single daily dose of tolbutamide and on a divided dose regimen (the two regimens are equally effective in their blood sugar lowering effect at all times throughout the 48 hours). — A plasma tolbutamide of 2–5 mg per cent was found to have some blood sugar lowering effect, and 24 h after a single oral dose effective levels were detectable in the plasma of some subjects. — Plasma insulin appears to respond to fluctuating glucose levels rather than to the tolbutamide levels and cannot fully account for the prolonged action of tolbutamide. — Tolbutamide given intravenously 3 h after a previous oral dose elicited a further rise in plasma insulin. The response was enhanced when the interval was increased to 18 h. A second peak in plasma insulin levels was often seen one hour after intravenous tolbutamide. — No insulin response was seen to repeated oral doses given at six to eight hour intervals. — An unexpected rise in plasma FFA was frequently observed ten minutes after intravenous tolbutamide. This may be attributed to the high circulating levels of tolbutamide which are measured as FFA by the method employed. — The mechanism of prolonged tolbutamide action remains unclear. These findings and their possible relationship to this action are discussed.

FUNCTIONING ISLET CELL ADENOMA IN THE NEWBORN

Persistent hypoglycemia in the neonate is rare and may be due to inborn errors of carbohydrate metabolism, islet cell tumors, or unknown causes. A patient with the onset of symptomaric hypoglycemia at 36 hours of age had persistent hypoglycemia in spite of therapy with corticosteroids, A.C.T.H., Diazoxide, glucagon, parenteral glucose and fructose. She showed a normal hyperglycemic response to glucagon. Plasma insulin values were not diagnostic. At surgery, at 7 weeks of age, a discrete islet cell adenoma was found and removed with the body and tail of the pancreas. The spleen was not removed. Following surgery, she had a transient hyperglycemia and required insulin for 8 days with a wound infection. She has remained normoglycemic.

The normal insulin response to glucose. The relationship between blood sugar and plasma insulin.

Plasma insulin values during a 50 g. oral glucose tolerance test were measured by immuno-assay in 34 control subjects. Peak insulin levels occurred within the first 60 minutes and the fasting level was approached by 120 minutes. The insulin curve closely resembled the blood sugar curve and a significant correlation was found between the blood sugar and plasma insulin values at 60, 90 and 120 minutes after oral glucose. The results suggest that the wide range in plasma insulin response is due in part at least to variations in the blood sugar. The results also tend to confirm that immuno-reactive insulin is biologically significant.

Experimental pancreas transplantation.

In nonimmune-modified pancreatectomized total pancrease allograft recipients, heterotopic transplants exhibit elevated plasma insulin values and decreased blood glucose determinations. This is not true of orthotopic allografts. Slight obstruction to venous outflow and concomitant duct ligation have been found to be important in genesis of necrotizing pancreatitis in heterotopic allografts. Rejection of a nonduct-ligated total pancreaticoduodenal allograft is signaled early by hyperamylasemia which appears earlier than the hyperglycemia of islet cell functional shutdown.

Plasma insulin levels during reactive hypoglycemia.

The plasma insulin response to an oral glucose load was studied in fourteen patients with reactive hypoglycemia—based on blood glucose values of 45 mg./100 ml. or below following 100 gm. of glucose. In reactive hypoglycemia, no single mechanism involving insulin secretion could explain the development of low blood glucose values. Six patients with reactive hypoglycemia demonstrated elevated plasma insulin values in association with normal blood glucose levels. In five patients the results of glucose tolerance tests suggested mild diabetes mellitus, and plasma insulin levels were increased. Three patients with reactive hypoglycemia had essentially normal glucose tolerance tests and no abnormality in plasma insulin response was noted.

Functioning Pancreatic Islet-Cell Adenoma Diagnosed Preoperatively by Means of Splanchnic Arteriography

THE DIAGNOSIS OF organic hypoglycemia due to an intraabdominal tumor usually can be made on the basis of clinical criteria. A high value of fasting plasma insulin may be helpful in differentiating a functioning islet-cell tumor of the pancreas from an intraabdominal fibrosarcoma, however, the value is normal in some patients with functioning β-cell tumor of the pancreas. 1 Even when the presence of hyperinsulinism has been determined, there remains the often difficult surgical problem of locating the functioning islet-cell tumor, particularly if the tumor is in the head of the pancreas. A method that demonstrates the presence and location of a functioning islet-cell tumor of the pancreas preoperatively would make the task of the surgeon much easier. The purpose of this paper is to report a case of proved organic hypoglycemia in which a functioning islet-cell adenoma of the pancreas was preoperatively diagnosed and located by means of selective