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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To evaluate the role of splanchnic and peripheral tissues in the disposal of an oral glucose load, splanchnic exchange of glucose, lactate, pyruvate, glycerol and amino acids was determined in ten healthy subjects in the basal state and for three hours following the oral ingestion of 100 gm. of glucose. Following glucose ingestion, splanchnic glucose output rose rapidly, reaching values two to three times the basal rate at fifteen minutes and returning to baseline by ninety minutes. A secondary rise in splanchnic glucose output occurred at 150 minutes and coincided with a secondary increment in arterial glucose. Total splanchnic glucose output over three hours was 40 plus or minus 3 gm., representing a total increase of only 15 plus or minus 3 gm. above basal splanchnic glucose output. The peak rise in blood glucose was directly proportional to the increase in splanchnic glucose output. Arterial concentrations of alanine, lactate and pyruvate rose by 15, 65 and 80 per cent, respectively, following oral glucose. These arterial elevations were preceded by a 75-100 per cent inhibition of splanchnic uptake of alanine and lactate; in the case of pyruvate there was a reversal from a net uptake in the basal state to a significant net splanchnic output after glucose ingestion. Arterial glycerol fell by 50 per cent and was accompanied by a comparable fall in splanchnic uptake. It is concluded that in normal, postabsorptive man, (a) the major portion of a 100 gm. oral glucose load is retained within the splanchnic bed; (b) only 15 per cent of the ingested glucose is available for disposal by peripheral tissues as increased (above-basal) glucose utilization; (c) the height and shape or the oral glucose tolerance curve are largely determined by the rate and pattern of splanchnic glucose escape; (d) glucose-induced hyperlactatemia, hyperpyruvicemia and hyperalaninemia are due at least in part, to altered splanchnic exchange of these substrates.
Diabetes 1975 May
PMID:Influence of oral glucose ingestion on splanchnic glucose and gluconeogenic substrate metabolism in man. 112 90

Although the stimulatory effect of glucagon on gluconeogenesis has been well demonstrated in certain systems in vitro, this effect has never been established in man. The present study was undertaken, therefore, to determine whether glucagon could stimulate gluconeogenesis from alanine in normal fasting man. Glucagon might stimulate this process by increasing the hepatic alanine uptake and/or by shunting the extracted alanine within the liver into the gluconeogenic pathway. In order to be able to examine these two aspects of gluconeogenesis, we combined the hepatic vein-brachial artery catheterization technic with an istopic infusion of alanine-14C. Alanine-14C specific activity was measured in whole blood and plasma by use of a rapid chromatographic technic. Since plasma contributed 93 per cent of the alanine extracted by the splanchnic bed with a specific activity three times that of the red blood cells, plasma alanine specific activity was used to study the conversion of alanine to glucose. A constant infusion of alanine-14C achieved a relatively stable arterial specific activity by forty minutes. The administration of glucagon by constant infusion (15-50 ng./kg./min.) had no affect on thf splanchnic extraction of alanine. Net splanchnic glucose-14C production, however, doubled during the glucagon infusion, and the conversion of alanine to glucose increased from 30 plus or minus 2 to 58 plus or minus 9 mumol/min. These data (1) demonstrate that in normal man fasted twelve to fourteen hours, glucagon at supraphysiologic levels can double the rate of gluconeogenesis from alanine and (2) indicate that this stimulatory effect of glucagon is exerted within the liver by shunting the extracted alanine toward new glucose formation rather than by increasing the hepatic extraction of alanine.
Diabetes 1975 Jun
PMID:Gluconeogenesis from alanine in normal postabsorptive man. Intrahepatic stimulatory effect of glucagon. 114 May 13

Renal substrate exchange was examined in five male patients with insulin-dependent diabetes mellitus of several years' duration. Insulin was withheld for twenty-four hours prior to the study. A renal vein was catheterized from the femoral vein, and PHA-clearance was employed for the determination of effective renal blood flow. None of the patients was in ketoacidosis, but all were moderately hyperglycemic in the fasting states (16.8 +/- 1.5 mmol/L.) (225-384 mg./100 ml.). Nevertheless, no net release of glucose from the kidney was detectable. Instead, there was a significant net renal uptake of glucose (320 +/- 80 mumol/min.). In addition, there was a significant net uptake of glycerol and a net release of pyruvate. Renal amino acid exchange was similar to that reported for healthy subjects: glutamine, glycine, proline, and citrulline were taken up and serine, alanine, cystine, tyrosine, and threonine were released by the kidney. It is concluded that (a) in nonketoacidotic diabetics there is no net production of glucose by the kidney; (b) renal amino acid exchange in diabetics is similar to that of healthy individuals; and (c) the kidney is not an important gluconeogenic organ in human diabetes.
Diabetes 1975 Aug
PMID:Renal substrate exchange in human diabetes mellitus. 115 36

Insulin antagonism characterizes infection, but the mechanism is unknown. Previous studies have been performed during the acute catabolic stage of infection, and the resultant metabolic changes reflect this decreased food intake and weight loss. To delineate metabolic alterations due to infection itself, rats with pyelonephritis induced by tail-vein injection of 1 ml. of Streptococcus faecalis (10(9) bacteria per milliliter) were studied two weeks later during a period of near-normal weight gain and food intake. Fasting growth hormone concentrations (nanograms per milliliter) in the pyelonephritic rats were nearly five times normal (45.8 vs. 9.9). Intra-arterial glucose and insulin tolerance tests were impaired. Early glucose-induced insulin release was depressed. Fat pads from infected rats manifested higher basal lipolysis per cell. Glycerol-mediated gluconeogenesis by liver slices was decreased. This pathway was unaffected by insulin in infected rats but readily inhibited in control rats. The following metabolic parameters were similar in control and infected animals: (in vivo) fasting concentrations of plasma glucose, free fatty acids, triglycerides, total corticoids, creatinine, insulin, glucagon, molar ratios of insulin and glucagon, glucose and insulin responses to tolbutamide, and glucagon and free fatty acid suppression after glucose; (in vitro) glucose metabolism by muscle and fat, epinephrine- and theophylline-stimulated lipolysis and re-esterification by epididymal fat pads, fasting hepatic glycogen content, glucose production by liver slices with and without alanine. No plasma insulin antagonist was found in the infected rats. Metabolic alterations in infected rats can be demonstrated independently of the associated catabolism. Increased growth hormone secretion cannot explain all of these changes.
Diabetes 1975 Oct
PMID:Metabolic studies in the pyelonephritic rat. 117 60

The effect of glucagon suppression by somatostatin upon endogenous hyperglycemia was studied in three forms of experimental insulin deficiency in dogs: alloxan diabetes, total pancreatectomy, and diazoxide administration. In six insulin-requiring alloxan-diabetic dogs deprived of insulin for 24 hr, mean plasma glucose declined to 77% +/- 6% of the baseline level of 350 +/- 41 mg/dl during 3 hr of glucagon suppression, significantly below the unsuppressed saline controls (p less than 0.01-0.05). When somatostatin was discontinued, glucagon rose and glucose increased 21% (p less than 0.05) in 30 min. Significant correlation between maximal changes in glucagon and glucose was observed (r = 0.81; p less than 0.001). Even during a 1-hr alanine infusion in such dogs, glucose declined an average of 36 +/- 9 mg/dl, instead of rising 51 +/- 7 mg/dl as in unsuppressed controls. Maximal changes in glucagon and glucose were correlated (r = 0.85; p less than 0.01). In eight depancreatized dogs pretreated intravenously with continuous insulin and glucose infusions, withdrawal of insulin was followed by a rise in extrapancreatic glucagon; mean plasma glucose rose from 212 +/- 43 to 415 +/- 80 mg/dl 270 min after the end of the insulin infusion. However, when glucagon was suppressed after insulin withdrawal, glucose remained below 240 mg/dl, significantly less than the controls (p less than 0.005); when somatostatin was stopped, glucagon rose and glucose increased 88 +/- 19 mg/dl within an hour. The rises in glucagon and glucose were significantly correlated (r = 0.68; p less than 0.05). Glucagon suppression by somatostatin during diazoxide-induced blockade of insulin secretion in four normal dogs reduced hyperglycemia significantly but did not prevent it. The results support the hypothesis that a relative or absolute excess of glucagon, as well as a relative or absolute deficiency of insulin, is etiologically important in the development of endogenous hyperglycemia in diabetes mellitus, the hyperglucagonemia probably mediating the glucose overproduction.
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PMID:The role of glucagon in the pathogenesis of the endogenous hyperglycemia of diabetes mellitus. 118 99

The minor components of hemoglobin which are increased in subjects with diabetes mellitus, hemoglobin Ala-c, were measured in identical twins concordant and discordant for diabetes to determine whether the observed increases represent a genetically determined abnormality. The mean values for the proportion of hemoglobins Ala-c in discordant twins differed markedly in the two members of the pair: 10.4 +/- 0.74 per cent for the diabetic twins and 6.85 +/- 0.33 for the nondiabetic twins (t = 4.3811, P less than 0.005). In concordant twins with juvenile onset diabetes, the mean proportion of Hb Ala-c was 11.4 per cent, and no marked differences were observed between members of twin pairs. Four pairs of identical twins concordant for maturity onset diabetes showed lower mean values for Hb Ala-c but did not show marked intra-pair differences. Thus, the abnormal proportions of hemoglobins Ala-c found in the presence of overt diabetes mellitus appear to be a manifestation of a metabolic abnormality of diabetes.
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PMID:Hemoglobin components in diabetes mellitus: studies in identical twins. 123 95

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.
Diabetes 1976 Mar
PMID:Tumor hypoglycemia: deficient splanchnic glucose output and deficient glucagon secretion. 125 10

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.
Diabetes 1976 Apr
PMID:Differential sensitivity of glycogenolysis and gluconeogenesis to insulin infusions in dogs. 126 37

Conflicting evidence has been reported on the metabolic fate of glucose following oral ingestion. We measured the metabolic pattern of gluconeogenic substrates as alanine, predominantly produced by muscle, and lactate after an oral glucose load in ten normal subjects and in eighteen non-insulin dependent diabetes mellitus (NIDDM) subjects. Neither in normal or NIDDM subjects were significant increases in plasma alanine observed, whereas a significant increase in plasma lactate was observed at 60, 90 and 120 min after a glucose load. Although a similar behaviour in plasma alanine and lactate between normal and NIDDM subjects was found, in NIDDM significantly higher levels of plasma alanine and lactate were found at each time. From these observations we conclude: 1) when glucose is ingested under post-absorptive conditions, since plasma alanine levels do not change concurrently with lactate increase, muscle tissue does not play a predominant role in glucose disposal 2) after an oral glucose load, the pattern of gluconeogenic precursors (alanine and lactate) is similar in normal and NIDDM subjects 3) the main cause of fasting and post-prandial hyperglycemia in NIDDM subjects may be due to an overproduction of alanine as well as lactate.
Diabetes Res 1992
PMID:Plasma alanine and lactate concentrations following glucose ingestion in normal and NIDDM subjects. 134 5

We have studied the activity of system A transport in skeletal muscle during experimental diabetes. Five days after streptozotocin injection, rats showed a marked hyperglycemia and a substantial decrease in the content of GLUT-4 protein in skeletal muscle and adipose tissue. Under these conditions, basal uptake of 2-(methyl)aminoisobutyric acid (MeAIB), an index of system A transport activity, was enhanced in extensor digitorum longus (EDL) muscles from diabetic rats compared to controls. Furthermore, insulin-stimulated MeAIB uptake by the incubated EDL and soleus muscles was markedly greater in diabetic than in control rats. The derepressive phase of adaptive regulation was partially blocked in the diabetic muscle, and incubation of muscles for 3 h in the absence of amino acids led to a lower stimulation of system A transport activity in muscles from diabetic groups compared to controls. We propose that the activated system A might participate in the enhanced alanine release from muscle cells that occurs in diabetes.
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PMID:System A transport activity is stimulated in skeletal muscle in response to diabetes. 138 24


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