Evaluation of ethanol hypoglycemia in man: turnover studies with C-6 14C glucose

Low Reported Adherence to the 2019 American Diabetes Association Nutrition Recommendations among Patients with Type 2 Diabetes Mellitus, Indicating the Need for Improved Nutrition Education and Diet Care

Patient adherence to guidelines is important for improved outcomes and prognosis. Nevertheless, many patients with type 2 diabetes mellitus (T2DM) do not comply with the recommendations regarding medication, physical activity, diet or self-care. The present cross-sectional study aimed to assess the level of adherence to the dietary recommendations issued by the American Diabetes Association (ADA) among patients with T2DM in Komotini, Greece. A total of 162 adults with T2DM (64.7 ± 10.6 years old), of which 41.4% were men, were recruited from the Sismanoglio Hospital and participated in the study. The level of adherence to individual recommendations issued by the ADA was assessed using yes/no questions. The overall adherence rate to the guidelines was low (41.2%). According to the multivariable analysis, age and medication therapy were identified as contributors to the compliance rate. No differences were noted in the total compliance rate between patients of different religious denominations (Muslims/Christians). Patients on oral antidiabetic agents (OAA) were more adherent compared with those on insulin therapy. A mere 3.7% of the participants had received nutrition education by a registered dietitian, 9.9% were following an individualized diet plan to improve glycemia, and 3.1% had set specific energy goals to reduce body weight. These findings are indicative of the need for the delivery of improved nutrition education.

Acute effects of traditional Japanese alcohol beverages on blood glucose and polysomnography levels in healthy subjects

Background. Alcohol consumption is a lifestyle factor associated with type 2 diabetes. This relationship is reportedly different depending on the type of alcohol beverage. The purpose of this study was to examine the acute effects of traditional Japanese alcohol beverages on biochemical parameters, physical and emotional state, and sleep patterns.

Methods. Six healthy subjects (three men and three women; age, 28.8 ± 9.5 years; body mass index, 21.4 ± 1.6 kg/m²) consumed three different types of alcohol beverages (beer, shochu, and sake, each with 40 g ethanol) or mineral water with dinner on different days in the hospital. Blood samples were collected before and 1, 2, and 12 h after drinking each beverage, and assessments of physical and emotional state were administered at the same time. In addition, sleep patterns and brain waves were examined using polysomnography.

Results. Blood glucose levels at 1 h and the 12-h area under the curve (AUC) value after drinking shochu were significantly lower than that with water and beer. The 12-h blood insulin AUC value after drinking shochu was significantly lower than that with beer. Blood glucose × insulin level at 1 h and the 2-h blood glucose × insulin AUC value with shochu were significantly lower than that with beer. The insulinogenic indexes at 2 h with beer and sake, but not shochu, were significantly higher than that with water. The visual analogue scale scores of physical and emotional state showed that the tipsiness levels with beer, shochu, and sake at 1 h were significantly higher than that with water. These tipsiness levels were maintained at 2 h. The polysomnography showed that the rapid eye movement (REM) sleep latency with shochu and sake were shorter than that with water and beer.

Conclusions. Acute consumption of alcohol beverages with a meal resulted in different responses in postprandial glucose and insulin levels as well as REM sleep latency. Alcohol beverage type should be taken into consideration for people with impaired glucose tolerance.

Impact of Alcohol on Glycemic Control and Insulin Action

Alcohol has profound effects on tissue and whole-body fuel metabolism which contribute to the increased morbidity and mortality in individuals with alcohol use disorder. This review focuses on the glucose metabolic effects of alcohol, primarily in the muscle, liver and adipose tissue, under basal postabsorptive conditions and in response to insulin stimulation. While there is a relatively extensive literature in this area, results are often discordant and extrapolating between models and tissues is fraught with uncertainty. Comparisons between data generated in experimental cell and animals systems will be contrasted with that obtained from human subjects as often times results differ. Further, the nutritional status is also an important component of the sometimes divergent findings pertaining to the effects of alcohol on the regulation of insulin and glucose metabolism. This work is relevant as the contribution of alcohol intake to the development or exacerbation of type 2 diabetes remains ill-defined and a multi-systems approach is likely needed as both alcohol and diabetes affect multiple targets within the body.

Strain-dependent differences for suppression of insulin-stimulated glucose uptake in skeletal and cardiac muscle by ethanol

BACKGROUND

Chronic ethanol (EtOH) consumption impairs the ability of insulin to suppress hepatic glucose production in a strain-dependent manner, with hepatic insulin resistance being greater in Long-Evans (LE) than Sprague-Dawley (SD) rats. We assessed whether strain differences exist for whole-body and tissue glucose uptake under basal and insulin-stimulated conditions and whether they were associated with coordinate strain-dependent elevations in muscle cytokines.

METHODS

Male rats (160 g) were provided the Lieber-DeCarli EtOH-containing (36% total energy) diet or pair-fed a control diet for 8 weeks. Rats were studied in the basal state or during a euglycemic hyperinsulinemic clamp, and whole-body glucose flux assessed using (3) H-glucose and in vivo tissue glucose uptake by (14) C-2-deoxyglucose.

RESULTS

EtOH impaired whole-body insulin-mediated glucose uptake (IMGU) more in SD than LE rats. This difference was due to impaired IMGU by gastrocnemius and heart in EtOH-fed SD versus LE rats. However, decreased IMGU in adipose tissue (epididymal and perirenal) produced by EtOH was comparable between strains. EtOH-induced insulin resistance in muscle from SD rats was associated with reduced AKT and AS160 phosphorylation and plasma membrane-localized GLUT4 protein as well as enhanced phosphorylation of c-Jun N-terminal kinase (JNK) and IRS-1 (S307), changes which were absent in muscle from LE rats. EtOH increased tumor necrosis factor alpha (TNFα) mRNA in gastrocnemius and fat under basal conditions in both SD and LE rats; however, hyperinsulinemia decreased TNFα in skeletal muscle from LE, but not SD rats. Interleukin (IL)-6 mRNA in gastrocnemius was increased under basal conditions and increased further in response to insulin in SD rats, but no EtOH- or insulin-induced change was detected in muscle IL-6 of LE rats.

CONCLUSIONS

These data indicate strain-dependent differences in EtOH-induced IMGU in skeletal and cardiac muscle, but not fat, associated with sustained increases in TNFα and IL-6 mRNA and JNK activation and decreased plasma membrane GLUT4 in response to insulin.

Sex differences in hepatic gluconeogenic capacity after chronic alcohol consumption

Alcohol-induced hypoglycemia has traditionally been attributed to the amount of ethanol consumed rather than any inherent decline in glucose output capacity by the gluconeogenic organs and/or an increase in skeletal muscle glucose uptake. Further, while the potential for sex differences that might impact glucose homeostasis following chronic alcohol consumption has been recognized, direct evidence has been noticeably absent. This paper will provide a brief review of past and present reports of the potential for sex differences in glucose homeostasis following chronic ethanol consumption. This paper will also provide direct evidence from our laboratory demonstrating sex differences from chronic alcohol consumption resulting in a decrement in glucose appearance and more importantly, a specific decline in hepatic gluconeogenic (HGN) capacity in the absence and presence of ethanol. All our studies involved 8 weeks of chronic alcohol consumption in male and female Wistar rats, as well as a 24 to 48 hour fast to deplete hepatic glycogen stores. Under the conditions of chronic alcohol consumption and an acute dose of ethanol, we provide in vivo evidence of an early decline in whole body glucose appearance in females fed an ethanol diet compared to controls. While the decline was also observed in males fed the alcohol diet, it occurred much later compared to ethanol fed females. The site for the decline in whole body glucose production (i.e., either the kidneys or the liver) was beyond the scope of our prior in vivo study. In a follow-up study using the in situ perfused liver preparation, we provide additional evidence for a specific reduction in HGN capacity from lactate in ethanol fed females compared to ethanol fed males in the absence of alcohol in the perfusion medium. Finally, employing the isolated hepatocyte technique, we report decrements in HGN from lactate in ethanol fed females compared to ethanol fed males in the presence of ethanol in the incubation medium. The mechanism for the specific decline in HGN within the liver of ethanol fed females remains to be determined. To the extent that our observations in animals can be extrapolated to humans, we conclude that alcoholic women are more susceptible to ethanol-induced hypoglycemia compared to alcoholic men.

Chronic alcohol consumption yields sex differences in whole-body glucose production in rats

AIMS

The effects of chronic alcohol consumption (8 weeks) on glucose kinetics, in the absence (water, 4 g/kg) and presence of an acute ethanol dose (4 g/kg), were examined in 48 h fasted male and female Wistar rats.

METHODS

Primed continuous infusions of [6-3H]- and [U-14C]glucose were employed to assess rates of glucose appearance (Ra), glucose disappearance (Rd), and apparent glucose carbon recycling.

RESULTS

After injecting the male and female controls with water, there were no significant alterations in glucose kinetics. Compared to controls, chronic alcohol-fed female animals (injected with water) demonstrated significantly lower: glucose Ra, blood glucose concentration, and apparent glucose carbon recycling for a majority of the experimental period. In separate groups injected with ethanol, the glucose Ra fell by 31% for male rats fed the control diet (MC), 43% for male rats fed the ethanol diet (ME), 29% for female rats fed the control diet (FC), and 42% for female rats fed the ethanol diet (FE). Further, compared to controls (MC and FC), the blood glucose concentration was significantly lower prior to and following the ethanol injection for FE. In addition, FE animals had significantly lower rates of glucose Ra and glucose carbon recycling compared to controls prior to and after the ethanol injection. ME animals demonstrated similar declines in glucose Ra (compared to FE), but only after the ethanol injection. Conversely, ME were able to match the decrease in glucose Ra with comparable declines in glucose Rd resulting in blood glucose concentrations that did not differ from controls.

CONCLUSIONS

Chronic alcohol consumption results in sex differences in whole-body glucose production and glucose regulation.

The inhibition of gluconeogenesis following alcohol in humans

Accurate quantification of gluconeogenic flux following alcohol ingestion in overnight-fasted humans has yet to be reported. [2-13C1]glycerol, [U-13C6]glucose, [1-2H1]galactose, and acetaminophen were infused in normal men before and after the consumption of 48 g alcohol or a placebo to quantify gluconeogenesis, glycogenolysis, hepatic glucose production, and intrahepatic gluconeogenic precursor availability. Gluconeogenesis decreased 45% vs. the placebo (0.56 +/- 0.05 to 0.44 +/- 0.04 mg. kg-1. min-1 vs. 0.44 +/- 0.05 to 0.63 +/- 0.09 mg. kg-1. min-1, respectively, P < 0. 05) in the 5 h after alcohol ingestion, and total gluconeogenic flux was lower after alcohol compared with placebo. Glycogenolysis fell over time after both the alcohol and placebo cocktails, from 1.46-1. 47 mg. kg-1. min-1 to 1.35 +/- 0.17 mg. kg-1. min-1 (alcohol) and 1. 26 +/- 0.20 mg. kg-1. min-1, respectively (placebo, P < 0.05 vs. baseline). Hepatic glucose output decreased 12% after alcohol consumption, from 2.03 +/- 0.21 to 1.79 +/- 0.21 mg. kg-1. min-1 (P < 0.05 vs. baseline), but did not change following the placebo. Estimated intrahepatic gluconeogenic precursor availability decreased 61% following alcohol consumption (P < 0.05 vs. baseline) but was unchanged after the placebo (P < 0.05 between treatments). We conclude from these results that gluconeogenesis is inhibited after alcohol consumption in overnight-fasted men, with a somewhat larger decrease in availability of gluconeogenic precursors but a smaller effect on glucose production and no effect on plasma glucose concentrations. Thus inhibition of flux into the gluconeogenic precursor pool is compensated by changes in glycogenolysis, the fate of triose-phosphates, and peripheral tissue utilization of plasma glucose.

Leucine and glucose turnover in chronic alcoholics during early abstinence and after an ethanol load

We studied leucine turnover using a primed infusion of [1-14C]-L-leucine and glucose turnover using a primed infusion of [6-3H]-D-glucose in five alcoholic patients without liver damage and five age-matched controls. Infusions were maintained for 6 hr, and at the end of the 3rd hour, a 0.8 g/kg iv ethanol load was administered in 20 min. Leucine flux, nonoxidative disposal and oxidation rates, and glucose rate of appearance were calculated during the 3rd and 6th hours of infusion. Ethanol disappearance rate and the percentage completely metabolized to CO2 and H2O in 3 hr were also calculated. Compared with controls, alcoholics had significantly higher basal leucine flux (55.6 +/- 12 vs. 37.3 +/- 9.3 microM/m2/min) and nonoxidative disposal (48.7 +/- 8.7 vs. 31.1 +/- 7.5 microM/m2/min). No differences were observed in basal glucose appearance rates in alcoholics and controls (397.6 +/- 115.2 vs. 349.4 +/- 120.6 microM/m2/min). Compared with controls, alcoholics had a higher alcohol disappearance rate (2.72 +/- 0.59 vs. 1.84 +/- 0.43 mM/kg/min) and percentage of ethanol metabolized to CO2 and H2O in 3 hr (40.6 +/- 10.2 vs. 22.9 +/- 6.9%). After the ethanol load, both leucine turnover and glucose rate of appearance decreased significantly only in alcoholics. There was a positive correlation between the change in leucine flux and ethanol disappearance rate and percentage metabolized to CO2 and H2O in alcoholics.

Does alcohol promote reactive hypoglycemia in the rat?

Alcohol induces a reactive hypoglycemia in man, but divergent results have been reported, in man and rats, on the effects of ethanol plus a carbohydrate load. The interactions between ethanol and glucose metabolism are complex. In the present study isocaloric solutions of glucose alone (A) or glucose plus alcohol (B) were administered in rats at the beginning of nighttime. Their effects were compared on blood glucose (BG) levels. Since rats don't drink alcohol spontaneously, glucose was given by mouth and alcohol through an intragastric catheter (IG); in the case of glucose alone half the load was ingested by mouth, and half IG. After administration, BG level was continuously determined in freely moving rats. It was shown that the latency to eat after the ingestion of glucose plus alcohol was significantly shorter and the size of the meal smaller. The postabsorptive hyperglycemia was significantly decreased in B as compared to A. The following hypoglycemia was more severe in B and it appeared earlier. In addition, a stress was applied after both A and B. It is well known that stress are potent stimuli of the sympathetic nervous system which inhibits insulin secretion. In both situations (A and B) with stress, the small preabsorptive hypoglycemia which appeared 4 min after the ingestion was suppressed. The hyperglycemia was higher in situation A with, than without, stress. The subsequent hypoglycemia was significantly lower. After stress in B, there was no difference in the peak of hyperglycemia but it appeared later. So, in rat the ingestion of alcohol together with an oral glucose load could trigger a reactive hypoglycemia. Stress greatly enhanced the phenomenon.

Ethanol administration diminishes the endotoxin-induced increase in glucose metabolism

The metabolism of ethanol (ETOH) is known to increase the cytosolic NADH/NAD ratio and consequently impairs hepatic glucose output in the fasted state. In contrast, one of the characteristic alterations in glucose metabolism produced by the administration of endotoxin is an increase in the de novo synthesis of glucose. Therefore, the present study tests the hypothesis that the acute administration of ETOH will prevent the endotoxin-induced increase in glucose production. In vivo glucose kinetics were determined by the infusion of [6-3H, U-14C]glucose in catheterized conscious rats. The intravenous infusion of tracer glucose, and ETOH (100 mg/100 g b.w./hr) or saline were started at the same time and both continued throughout the experiment. Two hours later the ETOH infusion rate was decreased to maintain the blood ETOH levels between 100 and 160 mg/dl. At 140 min, endotoxin (100 micrograms/100 g b.w.) was injected. ETOH alone did not alter basal values of plasma glucose (5 mM), glucose rate of appearance (Ra; 35 mumols/min/kg) or metabolic clearance (MCR; 7 ml/min/kg). Endotoxin alone increased plasma glucose (80%) and lactate (140%) concentrations, glucose Ra (60%) and recycling (40%) in saline-infused rats, whereas in ETOH-infused animals, plasma glucose and lactate levels were only elevated 40% and glucose Ra and recycling were unchanged. The results show that acute ETOH administration diminishes the increased glucose production and utilization seen in endotoxemia. The attenuation of the endotoxin effect by ethanol is due to inhibition of hepatic glucose production and peripheral glucose utilization.

The effect of ethanol on glucose production in phosphorylase b kinase deficiency

Glucose production was measured using stable isotopic techniques in two patients with phosphorylase b kinase deficiency before and after oral ethanol (0.75 g/kg). Glucose production was normal before the ethanol. In one patient, who did not take the full dose of ethanol, glucose production rose initially and then fell. In the other, glucose production fell steadily and in both patients blood lactate concentrations rose. Blood glucose concentrations decreased. Patients with this enzyme deficiency are dependent on the gluconeogenic pathway when fasting and, therefore, ethanol may be potentially hazardous.

Intermediary metabolite profiles during euglycemic glucose-insulin clamp: effects of ethanol

We evaluated the effects of different doses of i.v. alcohol on tissue insulin sensitivity, by means of insulin-glucose clamp technique, in 10 young healthy men. The most important intermediary metabolites were assayed. Insulin-dependent glucose disposal was impaired at different levels of alcoholemia, probably through an impairment of the glycolytic pathway. Exogenous insulin administration does not restore the more reduced redox state caused by alcohol oxidation. Alcohol does not interfere with the antiketogenic and antilipolytic insulin effects.

Limitation in glucose penetration from the liver into blood and other metabolic symptoms of ethanol withdrawal in rats

Studies were undertaken to determine whether the distribution of glycolytic intermediates between the blood and liver in rats would be changed upon ethanol consumption and after its withdrawal. More drastic impairment of energy metabolism appeared to occur after ethanol withdrawal than upon chronic ethanol ingestion. The major metabolic manifestations of withdrawal were severe hypoglycemia, hyperlactatemia and dramatic hypopyruvatemia. The liver/blood gradient of glucose attained a value of 4.2 after ethanol withdrawal, suggesting that glucose penetration from the liver into circulation became limited. Besides, glycogen was accumulated in the liver of withdrawn animals despite the severe hypoglycemia.

Hypoglycemia: causes, neurological manifestations, and outcome

During a 12-month prospective study there were 125 visits to the Harlem Hospital Emergency Room for symptomatic hypoglycemia. Sixty-five patients had obtundation, stupor, or coma; 38 had confusion or bizarre behavior; 10 were dizzy or tremulous; 9 had had seizures; and 3 had suffered sudden hemiparesis. Diabetes mellitus, alcoholism, and sepsis, alone or in combination, accounted for 90% of predisposing conditions; others included fasting, terminal cancer, gastroenteritis, insulin abuse, and myxedema. Average blood glucose levels were lower among comatose than among obtunded patients, but overlap was considerable, and overall there was little correlation among cause, blood glucose levels, and symptoms. Although mortality was 11%, only one death was attributable to hypoglycemia per se, and only four survivors had focal neurological residua.

Effects of chronic ethanol treatment on glucose tolerance, insulin response and circulating metabolites in the pregnant rat

The effects of chronic ethanol treatment on intravenous glucose tolerance and insulin response in non-pregnant and pregnant rats were studied. Basal circulating glucose, insulin, and ketone bodies levels were also determined during the treatment. Basal blood glucose concentration did not change during the ethanol treatment whereas plasma insulin levels were lower at the beginning of gestation and at the 15 and 18 days of pregnancy in ethanol-treated rats. Blood beta-OH-butyrate levels were higher and acetoacetate concentrations unchanged during the ethanol treatment, resulting in augmented beta-OH-butyrate/acetoacetate ratio. Intravenous glucose tolerance was not modified in ethanol-treated rats whilst the associated insulin response was lower in both non-pregnant and pregnant ethanol-treated rats. Data show that ethanol treatment during pregnancy alters glucose-insulin relationships despite being associated with unchanged maternal glycemia.

Ethanol administration fails to produce hypoglycemia in fasted chickens (Gallus domesticus)

Chickens weighing approx. 1500 g were fasted 64 hr and then continuously infused with [6-3H]glucose to determine effects of ethanol on plasma glucose concentrations and on rates of glucose turnover. Ethanol infusions (222 or 444 mumol/min X kg-1 body weight) did not cause hypoglycemia although the high dose infusion slightly decreased the rate of glucose turnover. Metabolite ratios measured in livers of chickens infused with the high dose of ethanol indicated that the hepatic cytosolic redox state was relatively unchanged. Chickens have an unusual resistance to ethanol-induced hypoglycemia.

Effects of chronic ethanol ingestion on male and female rat liver glycogen phosphorylase phosphatase

The effects of chronic ethanol ingestion on the interconversion of the active to the inactive form of glycogen phosphorylase by phosphorylase phosphatase was studied. Male and female rats also were compared. Chronic ethanol feeding decreased phosphorylase a and total phosphorylase activity in male rats. In females, no change was observed in phosphorylase a, whereas total phosphorylase activity was increased 73%. This was found to correlate with the relative activities of phosphorylase phosphatase. The data show differences between the two sexes with regard to the AMP inhibition of phosphorylase phosphatase and the caffeine stimulation of the phosphatase. Ethanol markedly enhanced the AMP inhibition of the phosphatase in males but had no effect in females. Further studies in females showed that ethanol completely obliterated the well documented stimulation of the phosphatase by caffeine; however, it did not alter the caffeine effect in males. These data suggest possible alterations in the tertiary structure of phosphorylase a.

Glucose turnover and metabolic and hormonal changes in ethanol-induced hypoglycaemia

Infusion of 67 g ethanol over four hours in fasted, non-obese normal men (a) induced hypoglycaemia by inhibiting gluconeogenesis; (b) produced noticeable increases in blood lactate, 3-hydroxybutyrate, and free fatty acid concentrations; (c) depressed plasma growth hormone concentrations, despite hypoglycaemia; and (d) raised plasma cortisol concentrations before significant hypoglycaemia occurred. These metabolic changes were explained by the reduction of redox state which accompanies ethanol oxidation. The pronounced changes in metabolic values recorded during this study suggested that the use of parenteral feeding regimens including ethanol needs to be reconsidered.

The mechanism of the acute hypoglycemic action of phenformin (DBI)

The mechanisms by which biguanide (phenformin) acutely brings about a reduction in blood glucose in diabetic subjects has been studied with the aid of C-6 14C glucose. Six diabetic subjects were studied, each at three separate dose levels of phenformin. Two of these same subjects were studied with placebo. Consistent and increasingly pronounced effects of drug versus placebo were noted as the level of biguanide was increased. Biguanide consistently lowered hepatic glucose output while not significantly affecting the removal of glucose from the circulation. It was noted that glucogenesis from lactate was not significantly curtailed. However, a lack of stimulation in Cori Cycle activity in the presence of significant elevations of circulating lactate were taken as an indication of inhibition of glucogenesis from this substrate. On balance, it is concluded that the acute hypoglycemic action of this biguanide is mediated primarily through a restriction in the supply of glucose from the liver to the circulation. The data support the contention that these drugs inhibit hepatic glucogenesis even though Cori Cycle activity may be increased and also suggest that a portion of the decrease in hepatic glucose supply may be the result of impaired glycogenolysis.

Effects of ethanol intake on lipoprotein lipase activity in adipose tissue of fasting subjects

Ethanol (ca. 1 g/kg body weight) was given alone or together with glucose or lipid (mixed triglycerides) perorally to young, fasting subjects. The changes with time (0-6 hr) of lipoprotein lipase activity (LLA) in adipose tissue, plasma glycerol, triglyceride, insulin, blood glucose, and alcohol concentrations were followed. A maximal mean blood alcohol concentration of 0.09% (w/v) was obtained 1 hr after ingestion with no apparent intoxicating effects. Ethanol intake prevented the previously observed [Nilsson-Ehle, P., S. Carlström, and P. Belfrage, Scand, J. Clin. Lab. Invest. 35:373 (1975)] glucose-induced rapid elevation of adipose tissue LLA but had small effects on this enzymatic activity when given alone or together with lipid. Confirming results by others, ethanol intake decreased plasma glycerol concentration and increased plasma triglycerides, especially after intake of lipid. It is suggested that ethanol intake interferes with the normal carbohydrate-induced elevation of adipose tissue LLA after a mixed meal, thereby decreasing the removal capacity for circulating dietary lipid and causing enhanced and prolonged alimentary hyperlipemia.

The use of isotope turnover techniques in the study of carbohydrate metabolism in man

It now appears that the bulk of methodological, analytical and interpretative problems associated with the use of isotope turnover techniques for the study of carbohydrate metabolism in man are resolved. As illustrated by a number of examples of the use of these techniques for the assessment of carbohydrate metabolism they seem, to the author, to have been more critically useful in the resolution of questions of (a) mechanism of hormone and drug action and (b) of interactions between metabolites, than they have been in defining pathological states, although the volume of information that is being accumulated is sure to prove useful for future research. Although it is this author's opinion that the employment of the radioactive isotopes at the low levels allowed by todays technology does not impose an unreasonable risk to the research subject, the promise of increased sensitivity for the detection of stable isotopes and the promise of their increased availability in a wide variety of compounds are factors that are sure to provide impetus for the wider use of these most valuable techniques in medical research.

Mechanism of action of phenethylbiguanide (phenformin) in man. III. interrelationship between ethanol and phenethylibiguanide (PBG) in normal and diabetic subjects

A standard 4-hr ethanol infusion (236 mg/min) after a 3-day fast with and without phenformin (25 mg q.i.d.), with blood drawn every hour for 8 hr, was performed on five normal subjects, eight obese nondiabetics, seven obese chemical diabetics, and four nonobese diabetics. Control infusion induced in all subjects a decline in blood sugar levels during and/or after the alcohol challenge, with a parallel decrease in basal plasma insulin. Hypoglycemia and the decrease in insulin secretion were associated with increased plasma free fatty acid concentration. Addition of phenethylbiguanide (PBG) to the preparatory 3-day fast resulted in a greater drop in the blood glucose levels of the normal control subjects, obese and nonobese diabetics; in the obese nondiabetics, however, significantly lower degree of blood glucose decrease than control was elicited. Furthermore, obese nondiabetics altered their blood glucose-insulin interaction with apparent increased responsivess of the B cells of PBG. The results suggest that effects of phenformin on blood glucose levels are more dependent on the metabolic state of the patient than on a property of the drug itself.