Nocturnal hypoglycemia in type 1 diabetes: an assessment of preventive bedtime treatments

OBJECTIVE: We assessed four putative bedtime treatments in the prevention of nocturnal hypoglycemia in type 1 diabetes. RESEARCH DESIGN AND METHODS: Plasma glucose concentrations were measured every 15 min from 2200 h through 0700 h in 21 patients with type 1 diabetes (mean +/- sd HbA(1C) = 7.1 +/- 1.0%) on five occasions with, in random sequence, bedtime (2200 h) administration of 1) no treatment, 2) a snack, 3) the snack plus the alpha-glucosidase inhibitor acarbose, 4) an uncooked cornstarch bar, or 5) the beta(2)-adrenergic agonist terbutaline. RESULTS: In the absence of a bedtime treatment, 27% of the measured nocturnal plasma glucose concentrations were less than 70 mg/dl (3.9 mmol/liter) in 12 patients; 16, 6, and 1% were less than 60, less than 50, and less than 40 mg/dl (3.3, 2.8, and 2.2 mmol/liter), respectively. Neither the snack (without or with acarbose) nor cornstarch raised the mean nadir nocturnal glucose concentration or reduced the number of low glucose levels or the number of patients with low levels. Terbutaline raised the mean nadir nocturnal glucose concentration (mean +/- se, 127 +/- 11 vs. 75 +/- 9 mg/dl; P < 0.001), eliminated glucose levels less than 50 mg/dl (P = 0.038), reduced levels less than 60 mg/dl (P = 0.005) to one, and reduced levels less than 70 mg/dl (P = 0.001) to five (four at 2215 h, one at 2230 h). However, it also raised glucose levels the following morning. CONCLUSIONS: Nocturnal hypoglycemia is common in aggressively treated type 1 diabetes. Bedtime administration of a conventional snack or of uncooked cornstarch does not prevent it. That of terbutaline prevents nocturnal hypoglycemia but causes hyperglycemia the following morning. The efficacy of a lower dose of terbutaline remains to be determined.     

Morning blood glucose determination in the monitoring of metabolic control in type 2 elderly diabetic cases treated by oral hypoglycemic agents]

Daily blood glucose profiles were measured in 163 Type 2 elderly diabetic cases to evaluate whether a fasting (before breakfast) or a post-prandial (after breakfast) blood glucose concentration is able to predict blood glucose values throughout the day. In the diet-treated alone group (n = 61), the percentage of daily blood glucose profiles having plasma glucose values less than the 08:00 hours (before breakfast) value were as follows: 59.0%, 32.8%, 59.0%, and 55.7% at 18.00 (before supper), 24.00, 03.00, 06.00 hours, respectively. In group treated by oral hypoglycemic agents (OHA) (n = 102), these were as follows: 45.1%, 26.5%, 52.9%, and 67.6%, respectively. In the OHA group, the mean plasma glucose value at 08:00 hours was significantly higher in patients with the lowest plasma glucose levels between 60-79 mg/dl than in patients with these levels between 80-99 mg/dl (103.7 +/- 19.6 vs 118.7 +/- 16.9 mg/dl, p < 0.01), but that at 10:00 hours was similar in the two groups (218.8 +/- 43.9 vs 214.5 +/- 40.1 mg/dl). In patients with lowest plasma glucose levels of between 60-99 mg/dl, the 08:00 hours value correlated positively with that of 24:00 (r = 0.40), 03.00 (r = 0.53), and the 06.00 hours value (r = 0.69), but no correlation was observed with the 18.00 hours value. On the other hand, the 10:00 hours value was not associated with these time-points values. Our results reveal that before breakfast plasma glucose values are more predictive of low blood glucose values in the night during sleep than after-breakfast blood glucose values, but do not predict low blood glucose values before supper in patients on OHA.     

Metabolic effects of sodium dichloroacetate in endotoxemic minipigs

Lactic acidosis is significant in the pathophysiology of endotoxicosis. By increasing the activity of pyruvate dehydrogenase, sodium dichloroacetate (DCA) decreases lactate production and may be useful as a therapy for endotoxic shock. Five (n = 5) 50-80-kg Yucatan minipigs were fitted with jugular, portal, hepatic vein, and carotid artery catheters, and hepatic artery and portal vein flow cuffs to quantitate transhepatic kinetics of glucose, lactate, and insulin. Three days later, they were placed in slings, and a primed-continuous intravenous infusion of 3-tritiated glucose was initiated to monitor whole body glucose kinetics. Following a 3-hour control period, an intravenous infusion of E. coli endotoxin (LPS) was administered at 15 micrograms/kg/hr for 6 hours. After 1 hour of LPS infusion, DCA was administered as a primed (30 mg/kg)-continuous (30 mg/kg/hr) intravenous infusion for 5 hours. These DCA-treated endotoxemic minipigs (group DE) were compared statistically to a group (n = 8) of minipigs given endotoxin only (group E). Group DE arterial lactate concentrations eventually decreased (19.2 +/- 1.0 mg/dl) significantly (P less than or equal to 0.05) below group E (39.3 +/- 7.7 mg/dl) in the last hour of DCA infusion. The progressive hypoglycemia of group DE decreased below that of group E and became significantly (P less than or equal to 0.05) lower in the last hour of the experiment (33.6 +/- 11.5 vs 50.6 +/- 10.0 mg/dl, respectively) due to decreased hepatic gluconeogenesis as evidenced by a lower relative rate of appearance (%Ra) of glucose and decreased hepatic glucose output and lactate extraction. A large relative decrease in pancreatic output of insulin in group DE contributed to the lower serum insulin levels than group E throughout the treatment period. Lethality in group DE (60%) was unaltered from that of group E (67%). Despite its ability to decrease arterial lactate concentrations, DCA alone does not appear to be an effective treatment for endotoxicosis.     

Beta1-adrenoceptor stimulation by high-dose terbutaline downregulates terbutaline-stimulated alveolar fluid clearance in ex vivo rat lung

Because high-dose terbutaline and isoproterenol (10(-3) M), beta2-adrenergic agonists, failed to increase alveolar fluid clearance, the mechanisms responsible for this effect were examined in ex vivo rat lungs. An isosmolar 5% albumin solution with Evans blue dye was instilled into the distal airspaces in isolated rat lungs that were then inflated with 100% oxygen at an airway pressure of 8 cm H2O in a 37 degrees C incubator. Alveolar fluid clearance was measured by the progressive increase in dye concentrations over 1 hour. The results indicated that: (1) although 10(-5) M terbutaline or isoproterenol increased alveolar fluid clearance, 10(-3) M terbutaline or isoproterenol did not; (2) both concentrations of terbutaline (10(-5), 10(-3) M) increased intracellular adenosine 3',5'-cyclic monophosphate in cultured type II alveolar epithelial cells; (3) instillation of atenolol, a selective beta1-adrenergic antagonist, in the presence of either 10(-3) M terbutaline or isoproterenol was associated with an increase in alveolar fluid clearance. These results suggested that beta1-adrenoceptor stimulation prevented the normal response to a beta2-adrenergic agonist. To further test this hypothesis, a selective beta1-adrenergic agonist, denopamine, was administered; these results showed that (4) 10(-3) M denopamine, a selective beta1-adrenergic agonist, inhibited the increase in alveolar fluid clearance in the presence of 10(-5) M terbutaline; (5) hypoxia for 2 hours did not alter the effects of terbutaline on alveolar fluid clearance. The mechanism for the inability of the alveolar epithelium to respond to high-dose terbutaline or isoproterenol with the normal upregulation of alveolar fluid clearance in ex vivo rats lungs appears to be mediated by beta1-adrenoceptor stimulation that subsequently suppresses the beta2-adrenergic response.     

The glucose-pH relationship in parapneumonic effusions.

Both a low pleural fluid glucose concentration and pleural fluid acidosis are markers of severe pleural inflammation, but the relationship between these phenomena has not been defined clearly. Therefore, we measured simultaneous pleural fluid glucose concentrations and pH in 25 consecutive parapneumonic pleural fluids. Seventeen effusions had a glucose concentration greater than 60 mg/dl (group 1, 126 +/- 7 mg/dl, mean +/- SEM), while eight had a pleural fluid glucose less than 60 mg/dl (group 2, 15 +/- 3 mg/dl, P less than .01). Pleural fluid pH was 7.35 +/- 0.03 in group 1 compared with 6.83 +/- 0.09 in group 2 (P less than .01). A significant correlation between pleural fluid glucose and pH was found (r = .81, P less than .01). Low-glucose, low-pH effusions were complicated (either loculated or empyemas). Uncomplicated effusions had glucose concentrations greater than 60 mg/dl and a pleural fluid pH greater than 7.30. The concomitant occurrence of low pleural fluid glucose and pH suggests that the mechanisms leading to these phenomena are interrelated.     

Hepatic and extrahepatic splanchnic glucose metabolism in the postabsorptive and glucose fed dog

In awake dogs we measured the glucose balance across the liver and extrahepatic splanchnic tissues in the postabsorptive state and during two hours of IV infusion of glucose or for three hours following ingestion of oral glucose and during four hours of sequential intraportal followed by oral glucose. The IV glucose infusion rate was adjusted to maintain a steady state glucose concentration of either euglycemic levels (insulin clamp, group 1, N = 4), 125 mg/100 mL above the postabsorptive glucose concentration (+125 mg glucose clamp, group 2, N = 3) or 200 mg/100 mL above basal glucose levels (+200 mg glucose clamp, group 3, N = 7). Oral glucose was given at a dose of either 1.5 g/kg (group 4, N = 7) or 2.5 g/kg (group 5, N = 12). In dogs that received IV glucose, basal gut glucose uptake (0.5 +/- 0.1 mg/min X kg) was stimulated by hyperglycemia (1.5 +/- 0.5 and 1.4 +/- 0.1 mg/min X kg for group 2 and 3, respectively, P less than 0.05). In these same animals basal hepatic glucose output (-2.7 +/- 0.3 mg/min X kg) was promptly suppressed and net hepatic glucose uptake occurred (2.8 +/- 0.2 and 2.4 +/- 0.5 mg/min X kg in group 2 and 3 respectively). Euglycemic hyperinsulinemia (group 1) suppressed postabsorptive hepatic glucose release but did not enhance glucose removal by either the liver or gut tissues. After oral glucose gut tissues released absorbed glucose into portal blood. Over three hours following the glucose meal 74% and 59% of the ingested glucose was absorbed in group 4 and 5, respectively. As with IV glucose, postabsorptive hepatic glucose production was suppressed and over the first two hours after feeding the liver took up glucose (3.4 +/- 1.0 and 3.1 +/- 0.7 mg/min X kg groups 4 and 5, respectively) at a rate similar to that seen with IV glucose. To further examine the effect of the route of glucose administration on liver glucose handling, hepatic glucose balance was measured serially over four hours in three dogs that received IV glucose into a mesenteric vein to produce portal hyperglycemia (+125 mg/dL portal glucose clamp N = 3). Oral glucose (2.5 mg/kg) was given at two hours, and the rate of the mesenteric glucose infusion adjusted to maintain portal glycemia constant. The hepatic glucose balance averaged 5.5 mg/min X kg over the 0 to 2 hour period and 4.2 +/- 1.0 mg/min X kg over the 2 to 4 hour time.(ABSTRACT TRUNCATED AT 400 WORDS)     

Modulation by pentobarbital of neutrophil responses to inhaled E. coli endotoxin in sheep: role of lung epithelium.

Neutrophils (PMNs) are implicated in the pathogenesis of acute respiratory distress syndrome (ARDS). The role of the epithelium in the modulation of PMN migration within the lungs was examined. Epithelial integrity and PMN concentrations in the lung air spaces and lymph were measured in sheep anaesthetized with either halothane (1-2.5%) or intravenous pentobarbital (12+/-4 mg x kg(-1) x h(-1)). Ventilation with an aerosol containing 25 mg Escherichia Coli endotoxin (lipopolysaccharide; LPS) effected neutrophil recruitment to the air spaces. Lymphatic clearance of aerosolized 99mTc-DTPA provided an index of epithelial integrity. Three hours after the deposition of LPS, the lung lining fluid of sheep anaesthetized with halothane (n=7) had 4.9+/-3.2x10(6) PMN.mL(-1), but the lung lymph had almost no PMNs (3+/-8%). Sheep anaesthetized with pentobarbital (n=6) had fewer PMNs in the air spaces (2.4+/-1.2X10(6) mL(-1)) and more PMNs in the lung lymph (30+/-20%). Control sheep (n=5) that received no LPS had almost no PMNs in the airspaces or lung lymph, regardless of the anaesthesia. Three additional sheep that remained awake after receiving LPS also had no PMNs in the lung lymph. The PMN fraction in the lung lymph correlated well with the extra-alveolar epithelial permeability measured by lymphatic clearance of aerosolized diethylenetriamine penta-acetic acid (r=0.81, p<0.001). Aerosolized lipopolysaccharide recruits neutrophils into the lungs of sheep, but they appear to remain in the airspaces unless extra-alveolar permeability is increased by agents such as pentobarbital.     

The effect of age and glucose concentration on insulin secretion by the isolated perfused rat pancreas

Age changes in the beta-cell's sensitivity to glucose as well as in its overall capacity to secrete insulin may play a part in the glucose intolerance of aging. The isolated perfused rat pancreas preparation was used to study the effect of age and glucose level on insulin secretion. Overnight-fasted male Wistar 12- and 23-month-old rats had basal plasma glucose levels of 106 +/- 4 (SE) and 100 +/- 4 mg/dl. Perfusate glucose levels were raised from 80 mg/dl to either 150, 220, or 360 mg/dl for 50 min (n = 6 to 8 in each group). Insulin secretion followed the typical biphasic pattern of an early spike and fall, followed by a sustained gradual increase at both ages. First-phase (0-10 min) insulin secretion in the old rats was significantly lower at 150 (184 vs. 524 microU/min, P less than 0.05) and 220 mg/dl (327 vs. 644 microU/min, P less than 0.05), while it was nearly identical at 360 mg/dl. Although lower in the old rats, second-phase (11-50 min) insulin secretion was not statistically significantly different for each glucose level. When first- and second-phase insulin secretion rates were combined, the old rats' insulin secretion was only lower at the 150 mg/dl level (248 vs. 426 microU/min, P less than 0.05). Thus, at the more physiological glucose level, old rats showed a significantly lower response, while at the higher levels insulin secretion was similar. This diminishing age effect with increasing glucose dose suggests a defect in islet sensitivity to glucose rather than a diminished capacity to secrete insulin.     

Correlation between levels of tumour necrosis factor-alpha and levels of pH, glucose, and lactate dehydrogenase in parapneumonic effusions

OBJECTIVES: This study was undertaken to investigate the correlation, which has not been previously investigated, between levels of tumour necrosis factor-alpha (TNF) and levels of pH, glucose, and lactate dehydrogenase (LDH) in pleural fluid of patients with uncomplicated parapneumonic effusion (UCPPE), and patients with complicated parapneumonic effusion (CPPE). METHODS: Using a commercially-available high sensitivity ELISA kit, levels of TNF were measured in pleural fluid of patients with UCPPE (n = 23), and CPPE (n = 15), and were compared with levels of pH, glucose, and LDH in these two groups. RESULTS: The mean +/- SD values of pleural fluid TNF, pH, glucose, and LDH in the UCPPE group were 11.05 +/- 7.65 pg/ml, 7.41 +/- 0.08, 125 +/- 48 mg/dl, and 306 +/- 182 IU/l, respectively. In the CPPE group the values were 56.07 +/- 28.5 pg/ml, 6.82 +/- 0.25, 42 +/- 36 mg/dl, and 2096 +/- 1916 IU/l, respectively. The only significant correlation, which was negative, was found between levels of TNF and pH in the CPPE group (r = -0.62, P = 0.01). Levels of pleural fluid TNF and LDH were significantly higher, and levels of glucose were significantly lower in the CPPE group than in the UCPPE group (P < 0.0001). CONCLUSIONS: This study demonstrates, for the first time that TNF levels correlate inversely with levels of pH in pleural fluid of patients with CPPE but not of patients with UCPPE. This correlation may, in part, explain the pathophysiology of the pleural complications which occur in the presence of CPPE.     

Control of lung surfactant by ventilation, adrenergic mediators, and prostaglandins in the rabbit.

In a previous study, we showed that increasing minute ventilation (VE) in rabbit lung by adding a dead space augmented pulmonary surfactant in the airspaces by a cholinergically mediated mechanism. Using the same model in the present study of 148 rabbits, we found that increasing VE augmented airspace phospholipid, the main component of surfactant, from 2.50 +/- 0.61 (mean +/- SD) mg per g of lung during normal VE to 3.15 +/- 1.22 (mean +/- SD) mg per g of lung during increased VE (P = 0.02). Both blocking beta-adrenergic receptors with propranolol or sotalol and inhibiting prostaglandin synthetase with indomethacin or sodium meclofenamate prevented the expected increase in phospholipid during increased VE (P is less than 0.05). The beta-2 agonist, terbutaline, increased phospholipid by 43 per cent during normal VE (P is less than 0.01), and propranolol blocked this increase (P is less than 0.05). Isoproterenol, arachidonic acid, prostaglandins E1, E2, F2alpha, and a cyclic endoperoxide analog of prostaglandin H2 (U-46619) injected during normal VE failed to increase phospholipid. We concluded that acetylcholine (previous study), beta-adrenergic mediators, and prostaglandins are involved in controlling alveolar surfactant during increased VE.     

Comparison of usefulness of sodium bicarbonate versus sodium chloride to prevent contrast-induced nephropathy in patients undergoing an emergent coronary procedure

In the case of an emergency coronary procedure where the risk of contrast-induced nephropathy is especially high, there are few reliable methods to attenuate renal injury. We examined the efficacy of sodium bicarbonate for the prevention of contrast-induced nephropathy in patients undergoing an emergency coronary procedure. We enrolled 59 patients who were scheduled to undergo an emergency coronary angiography or intervention. These patients were randomized to receive a 154-mEq/L infusion of sodium bicarbonate (n = 30) or sodium chloride (n = 29), as a bolus of 3 ml/kg/hour for 1 hour before the administration of contrast, followed by an infusion of 1 ml/kg/hour for 6 hours during and after the procedure. In the sodium bicarbonate group, serum creatinine concentration remained unchanged within 2 days of contrast administration (1.31 +/- 0.52 to 1.31 +/- 0.59 mg/dl), whereas it increased in the sodium chloride group (1.32 +/- 0.65 to 1.52 +/- 0.92 mg/dl, p = 0.01). The incidence of contrast-induced nephropathy (an increase >0.5 mg/dl or >25% in serum creatinine concentration within 2 days of contrast) was significantly lower in the sodium bicarbonate group than in the sodium chloride group (7% vs 35%, p = 0.01, risk ratio 0.19, 95% confidence interval 0.046 to 0.80). In conclusion, hydration with sodium bicarbonate is more effective than with sodium chloride for the prevention of contrast-induced nephropathy in patients undergoing an emergency coronary procedure.     

Glucose homeostasis. Comparison between hypothermic and normothermic cardiopulmonary bypass.

STUDY OBJECTIVE: Disturbance in blood glucose homeostasis during cardiac surgery may cause visceral and metabolic alterations. Hypothermic CPB induces glucose and hormonal changes. As normothermic CPB is used at some institutions, a comparison of blood glucose and plasma hormones between hypothermic and normothermic CPB was performed. DESIGN: Prospective nonrandomized study. SETTING: University cardiac center. PATIENTS: Twenty-two nondiabetic adults undergoing elective coronary bypass and/or valvular surgery. INTERVENTIONS: Group 1 (n = 12) underwent hypothermic CPB (25 degrees C) and group 2 (n = 10) normothermic CPB (37 degrees C). In both groups nonpulsatile CPB was achieved with a membrane oxygenator and dextrose-free crystalloid priming. Dextrose was not administered during surgery but was infused postoperatively (125 mg/kg/h). MEASUREMENTS AND RESULTS: Eight blood samples were drawn during the period of arrival in the operating room (control) to the third postoperative hour. During hypothermic CPB in group 1, blood glucose level increased to 154 +/- 20 mg/dl (mean +/- SD) associated with a decrease in plasma insulin and an increase in epinephrine, despite a decrease in cortisol and growth hormone. During rewarming, the blood glucose value continued to increase (to 197 +/- 35 mg/dl) associated with an increase in glucagon, growth hormone and catecholamines, despite a 374 percent increase in insulin. During CPB in group 2, insulin, glucagon, cortisol and catecholamines were significantly higher than during hypothermic CPB so that the blood glucose level was not significantly different between the two groups during CPB. Blood glucose value was higher in group 1 than in group 2 at closure of the chest (208 +/- 30 vs 175 +/- 19 mg/dl, respectively, p less than 0.02) and at the third postoperative hour (271 +/- 30 vs 221 +/- 51 mg/dl, p less than 0.01). In both groups, however, the postoperative increase in blood glucose was accompanied by a similar increase in insulin, cortisol and catecholamines but glucagon was lower after hypothermic CPB. CONCLUSIONS: Hyperglycemia occurred perioperatively in cardiac surgery with dextrose-free priming both during hypothermic and normothermic CPB but normothermic CPB resulted in a slow and steady increase in both glucose and insulin concentrations without the major perturbations that occurred with hypothermic CPB. Postoperatively, higher blood glucose was observed in the hypothermic CPB group.     

Decrease in insulin binding to aortic endothelial cells cultured with high glucose concentration

We studied the effects of glucose on specific insulin binding to cultured endothelial cells from the bovine aorta. We cultured the cells in Dulbecco's modified Eagle's medium, containing 100 or 300 mg/dl glucose or 100 mg/dl glucose plus 200 mg/dl mannitol. We added 125I-insulin to monolayers of these cells and counted the radioactivity resulting. Specific insulin binding increased with time and dosage. Maximal binding resulted from 0.17 nM 125I-insulin being incubated for 30 min at 37 degrees C, and amounted to 0.35% per 10(5) cells being bound in cultures of 100 mg/dl glucose. The higher concentration of glucose led to significantly less binding (P less than 0.05) (0.24 +/- 0.03% vs. 0.38 +/- 0.02%, n = 6). The addition of mannitol, on the other hand, did not affect binding. All three incubation conditions produced curvilinear competition curves. Scatchard analysis showed that insulin bound significantly less (P less than 0.05) to endothelial cells in 300 mg/dl glucose than to those in 100 mg/dl glucose (4.0 +/- 1.2 nmol/l vs. 12.8 +/- 3.1, n = 6, mean +/- SEM). Insulin binding capacity, however, did not change. We conclude that glucose can reduce insulin binding to endothelial cells and that it may reduce receptor-related insulin transport into and out of the cells.     

The effect of short-term glycemic regulation with gliclazide and metformin on postprandial lipemia.

AIM: Exaggerated postprandial lipemia is now accepted as an independent risk factor in atherogenesis in type 2 diabetes mellitus. We investigated if better glycemic control improves fasting and postprandial lipid profile in type 2 diabetic patients in the short-term. METHODS: Thirty-two type 2 diabetic patients were studied before and after desired glycemic regulation with gliclazide and metformin. Basal levels of glucose, total cholesterol, high density lipoprotein, low density lipoprotein, triglyceride, insulin, and C-peptide were evaluated at fasting state. Afterwards, patients were given a standard 400-kcal mixed meal as a breakfast, contaning 35 % fat. At the 2nd and the 4th hours after the breakfast, postprandial glucose, triglyceride, insulin, and C-peptide levels were determined again. RESULTS: Significant decrease was observed in total cholesterol levels after better glycemic regulation (p<0.05). Besides, triglyceride levels decreased significantly from 175.36+/-17.85 mg/dl to 138.73+/-14.93 mg/dl at fasting state (p<0.05), from 197.26+/-20.85 mg/dl to 154.15+/-14.61 mg/dl at the 2nd hour after mixed meal (p<0.05), and from 209.63+/-28.54 mg/dl to 155.63+/-15.68 mg/dl (p<0.05) at the 4th hour after the mixed meal, when better glycemic profile was provided. Area under curve for triglyceride levels decreased significantly with the better glycemic regulation (p<0.01). CONCLUSIONS: Improved glycemic regulation can lower the raised fasting and postprandial triglyceride levels which are important atherosclerotic risk factors in diabetic patients even in short-term. Since this improvement in triglyceride levels comes early, diabetic patients can be evaluated for fasting and postprandial triglyceride levels in the first month of therapy.     

The role of glucagon in the pathogenesis of the endogenous hyperglycemia of diabetes mellitus.

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.     

Counterregulatory responses to insulin-induced glucose reduction in the elderly

The impact of age on counterregulatory responses to moderate reductions in blood glucose induced by a constant insulin infusion (20 mU/m2 X min) was studied in normal young (n = 7; aged 20-42 yr) and old (n = 7; aged 66-77 yr) nonobese subjects. Insulin was infused until the whole blood glucose level fell to or below 60 mg/dl. This required an infusion time of 39 +/- 3 (+/- SE) min in the young and 36 +/- 3 min in the old. Mean basal glucose [young, 88 +/- 2 (+/- SE); old, 88 +/- 2 mg/dl), minimum glucose (young, 51 +/- 2; old, 54 +/- 1 mg/dl), time to nadir (young, 48 +/- 3; old, 44 +/- 3), and time to recovery were similar in both groups. Maximal (young, 40.3 +/- 2.3; old, 42.1 +/- 3.3 microU/ml) insulin levels were also similar. Basal and maximal levels of glucagon, epinephrine, and GH were similar in the two groups. Although basal norepinephrine values were higher in the old subjects (young, 243 +/- 38; old, 364 +/- 23 pg/ml; P = 0.02), increments above basal during reduction in blood glucose were not affected by age. Basal cortisol values were similar (young, 13.7 +/- 1.4; old, 14.0 +/- 0.7 micrograms/dl), but maximum cortisol responses were slightly greater in the old subjects (young, 14.6 +/- 1.0; old, 17.7 +/- 0.9 micrograms/dl; P = 0.03). These studies indicate that hormonal responses and counterregulatory efficiency during modest reductions in blood glucose are preserved in healthy elderly subjects.     

Emerging risk factors and early atherosclerosis indices in subjects with impaired glucose tolerance

AIM: To evaluate the response to an oral lipid overload, inflammatory markers and carotid intima-media thickness in subjects with impaired glucose tolerance. METHODS: 54 subjects, both sexes, 58 y-old average were submitted to 1) Clinical evaluation 2) Glucose tolerance test with 75 g glucose; classified as normal (2 h plasma glucose<140 mg/dl, n=37) or IGT (2 h G 140-200 mg/dl, n=17), 3) 12 h fasting sample (plasma glucose, lipids, C-reactive protein, fibrinogen and HOMA-IR calculation); 4 and 6 h after the oral lipid overload (1000 kcal, lipids 65 g) glycemia, fibrinogen and triglycerides were reevaluated. Intima-media thickness was calculated by the average of 6 measurements (3 highest of each carotid) evaluated by ultrasonography (7 MHZ transducer). RESULTS: The IGT group had higher (P<0.001) fasting plasma glucose (89.4 +/- 13 vs 104.4 +/- 8 mg/dl), HOMA-IR (1.69 +/- 1.2 vs 2.93 +/- 2.2) and waist (91 +/- 14 vs 101 +/- 9 cm), similar fasting lipids, intima-media thickness (P=0.58) and post-oral lipid overload triglycerides (P=0.74), but higher fibrinogen (284.3 +/- 6 and 305 +/- 10 mg/dl, P=0.05) and C-reactive protein (2.11 +/- 0.33 and 4.19 +/- 0.65 mg/l, P=0.003). C-reactive protein was positively correlated with HOMA-IR (r=0.45, P=0.001), fasting plasma glucose (r=0.43, P=0.002) and waist (r=0.45, P=0.0006), but not with postprandial lipids.CONCLUSION: A higher C-reactive protein in IGT, and its positive correlation with insulin resistance indices, but not with postprandial lipaemia, suggests that the clustering of these factors, characteristic of the metabolic syndrome, occurs earlier than postprandial lipid abnormalities.     

Impaired splanchnic and peripheral glucose uptake in liver cirrhosis.

BACKGROUND/AIM: Patients with liver cirrhosis are insulin-resistant and frequently glucose-intolerant. Although peripheral glucose uptake has been shown to be impaired in liver cirrhosis, little is known about the significance of splanchnic (hepatic) glucose uptake after oral glucose load. METHODS/RESULTS: We performed an oral glucose tolerance test and euglycemic hyperinsulinemic clamp with oral glucose load for eight patients with liver cirrhosis and eight patients with chronic active hepatitis. The patients with liver cirrhosis had higher plasma glucose levels 2 h after glucose load than those with chronic active hepatitis (228+/-22 mg/dl vs. 102+/-9 mg/dl, p<0.01). Using the euglycemic hyperinsulinemic clamp with oral glucose load, we simultaneously measured peripheral and splanchnic glucose uptake. Peripheral glucose uptake in liver cirrhosis was 6.1+/-0.7 mg x kg(-1) x min(-1), which was lower than that in healthy volunteers (10.5+/-0.9 mg x kg(-1) x min(-1), p<0.05) and in chronic active hepatitis (8.4+/-0.3 mg x kg(-1) x min(-1), p<0.05). Furthermore, splanchnic glucose uptake in liver cirrhosis was much lower (20.1+/-3.4%) than in healthy volunteers (36.0+/-4.0%, p<0.05) and in chronic active hepatitis (37.2+/-3.1%, p<0.05). CONCLUSION: These results suggest that glucose intolerance in patients with liver cirrhosis is caused by a defect of the glucose uptake of both splanchnic and peripheral tissues.     

Net hepatic lactate balance following mixed meal feeding in the four-day fasted conscious dog

The present experiments were undertaken to determine whether four days of fasting and marked hepatic glycogen depletion would alter the effect of mixed meal feeding on net hepatic lactate balance in the conscious dog. Dogs were fasted for four days and were then fed a mixed meal over a ten-minute period. Net hepatic glucose and lactate balance were monitored for the next eight hours using the A-V difference technique. The arterial plasma glucose level rose to a maximum of 121 +/- 3 mg/dL three hours after feeding and then decreased. Net hepatic glucose output declined to 0.44 +/- 0.44 mg/kg/min but the liver never became a net consumer of glucose. The arterial blood lactate level rose from 678 +/- 71 to 1000 +/- 158 mumol/L as the liver switched from net lactate uptake (12.2 +/- 2.0 mumol/kg/min) to net lactate production (4.3 +/- 1.7 mumol/kg/min). Over the course of the eight-hour postprandial period 25 g of glycogen were deposited in the liver. The net hepatic uptake of the gluconeogenic amino acids rose from 6.1 +/- 1.2 mumol/kg/min to a peak of 15.4 +/- 4.3 mumol/kg/min one hour after feeding. Net hepatic uptake of glycerol fell from 3.0 +/- 0.3 mumol/kg/min to an average of 1.5 +/- 0.4 mumol/kg/min. The plasma insulin level increased from 13 +/- 2 microU/mL at 3.5 hours and fell to 32 +/- 7 microU/mL by 8 hours. The plasma glucagon level rose from 22 +/- 3 pg/mL to 93 +/- 12 pg/mL 1.5 hours after feeding and fell to 68 +/- 6 pg/mL 8 hours after feeding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fenfluramine in the treatment of non-insulin-dependent diabetics: hypoglycemic versus anorectic effect

A few studies have suggested that the anorectic drug fenfluramine has a hypoglycemic effect. The major problem in interpreting those studies, however, is the difficulty in dissociating the effect of weight loss on blood glucose from the direct effect of fenfluramine. In a double-blind study of 28 diabetic females treated with oral hypoglycemic agents, a significant decrease in fasting blood glucose (from 195 +/- 17 mg/dl to 152 +/- 15 mg/dl after four weeks, and to 155 +/- 14 mg/dl after eight weeks) was observed in fenfluramine-treated patients (n = 14). Corresponding values in the placebo group were 185 +/- 12 mg/dl and 201 +/- 16 mg/dl respectively. Glucose tolerance after a standard meal was also improved after fenfluramine treatment. Weight loss was minimal and not significantly different for the two groups. From these observations, it can be concluded that fenfluramine has a lowering effect on blood glucose which is independent of its effect on weight.