Effects of free fatty acids, insulin, glucagon and adrenaline on ketone body production in humans

Effect of cigarette smoking and of a transdermal nicotine delivery system on glucoregulation in type 2 diabetes mellitus

The effect of nicotine absorbed transdermally from a patch (TNS) and from cigarette smoking on insulin secretion and action in Type 2 diabetes has been compared. Twelve Type 2 diabetic smoking patients, aged 51 y, with diabetes for 9 y, treated either with diet and/or oral hypoglycaemic agents, were studied on three occasions, according to a double-blind, placebo-controlled, cross-over design. The subjects were investigated 12 h after their last cigarette or application of one patch of TNS 30 cm2 or TNS placebo, or whilst smoking their usual cigarette. Insulin secretion was assessed by a glucagon (1 mg IV) stimulation test. On a second occasion, insulin action was assessed by a hyperglycaemic-hyperinsulinaemic clamp, the spontaneous hyperglycaemia of the fasting state (8.61 mmol.l-1) being maintained during a 4 h insulin infusion (at 0.1 mU.kg-1.min-1 for the initial 2 h, and 1 mU.kg-1.min-1 during the last 2 h). TNS and the cigarette did not affect endogenous insulin secretion as compared to placebo. During the initial 2 h of the clamp study, plasma insulin increased from 88 to 155 pmol.l-1, hepatic glucose production (3-3H-glucose) was less suppressed after TNS (4.31 mumol.kg-1.min-1) than after placebo (2.5 mumol.kg-1.min-1), but was more suppressed than after cigarette smoking (5.61 mumol.kg-1.min-1). In the last 2 h of the clamp (plasma insulin 646 pmol.l-1), glucose utilization was less stimulated after TNS (36.1 mumol.kg-1.min-1) vs placebo (39.8 mumol.kg-1.min-1), but more than after cigarette smoking (33.6 mumol.kg-1.min-1), primarily because of a decrease in glucose storage.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic mechanisms contribute to the late phase of hypoglycemic glucose counterregulation in humans by stimulating lipolysis

Three studies were performed on nine normal volunteers to assess whether catecholamine-mediated lipolysis contributes to counterregulation to hypoglycemia. In these three studies, insulin was intravenously infused for 8 h (0.30 mU.kg-1.min-1 from 0 to 180 min, and 0.40 mU.kg-1.min-1 until 480 min). In study I (control study), only insulin was infused; in study II (direct + indirect effects of catecholamines), propranolol and phentolamine were superimposed to insulin and exogenous glucose was infused to reproduce the same plasma glucose (PG) concentration of study I. Study III (indirect effect of catecholamines) was the same as study II, except heparin (0.2 U.kg-1.min-1 after 80 min), 10% Intralipid (1 ml.min-1 after 160 min) and variable glucose to match PG of study II, were also infused. Glucose production (HGO), glucose utilization (Rd) [3-3H]glucose, and glucose oxidation and lipid oxidation (LO) (indirect calorimetry) were determined. In all three studies, PG decreased from approximately 4.8 to approximately 2.9 mmol/liter (P = NS between studies), and plasma glycerol and FFA decreased to a nadir at 120 min. Afterwards, in study I plasma glycerol and FFA increased by approximately 75% at 480 min, but in study II they remained approximately 40% lower than in study I, whereas in study III they rebounded as in study I (P = NS). In study II, LO was lower than in study I (1.69 +/- 0.13 vs. 3.53 +/- 0.19 mumol.kg-1.min-1, P less than 0.05); HGO was also lower between 60 and 480 min (7.48 +/- 0.57 vs. 11.6 +/- 0.35 mumol.kg-1.min-1, P less than 0.05), whereas Rd was greater between 210 and 480 min (19 +/- 0.38 vs. 11.4 +/- 0.34 mumol.kg-1.min-1, respectively, P less than 0.05). In study III, LO increased to the values of study I; between 4 and 8 h, HGO increased by approximately 2.5 mumol.kg-1.min-1, and Rd decreased by approximately 7 mumol.kg-1.min-1 vs. study II. We conclude that, in a late phase of hypoglycemia, the indirect effects of catecholamines (lipolysis mediated) account for at least approximately 50% of the adrenergic contribution to increased HGO, and approximately 85% of suppressed Rd.

ACE-inhibition increases hepatic and extrahepatic sensitivity to insulin in patients with type 2 (non-insulin-dependent) diabetes mellitus and arterial hypertension

To assess the effects of ACE-inhibition on insulin action in Type 2 (non-insulin-dependent) diabetes mellitus associated with essential hypertension, 12 patients with Type 2 diabetes (on diet and oral hypoglycaemic agents) and arterial hypertension were examined on two occasions, in a single blind, cross-over study after two days of treatment with either captopril or a placebo. The study consisted of a euglycaemic-hyperinsulinaemic clamp (two sequential steps of insulin infusion at the rates of 0.25 mU.kg-1.min-1 and 1 mU.kg-1.min-1, 2 h each step), combined with an infusion of 3-3H-glucose to measure the rate of hepatic glucose production and that of peripheral glucose utilization. The results show that blood pressure was lower after captopril (sitting, systolic 148 +/- 5 mm Hg, diastolic 89 +/- 2 mm Hg) compared to placebo (155 +/- 6 and 94 +/- 2 mm Hg) (p less than 0.05). Captopril treatment resulted in a more suppressed hepatic glucose production (2.7 +/- 0.4 vs 4.94 +/- 0.55 mumol.kg-1.min-1), and a lower plasma non-esterified fatty acid concentration (0.143 +/- 0.05 vs 0.200 +/- 0.05 mmol/l) (captopril vs placebo, p less than 0.05) at the end of the first step of insulin infusion (estimated portal plasma insulin concentration 305 +/- 28 pmol/l); and in a greater glucose utilization (36.5 +/- 5.1 vs 28 +/- 3.6 mumol.kg-1.min-1, p less than 0.001) at the end of the second step of insulin infusion (arterial plasma insulin concentration of 604 +/- 33 pmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Defective glucose counterregulation after subcutaneous insulin in noninsulin-dependent diabetes mellitus. Paradoxical suppression of glucose utilization and lack of compensatory increase in glucose production, roles of insulin resistance, abnormal neuroendocrine responses, and islet paracrine interactions

To characterize glucose counterregulatory mechanisms in patients with noninsulin-dependent diabetes mellitus (NIDDM) and to test the hypothesis that the increase in glucagon secretion during hypoglycemia occurs primarily via a paracrine islet A-B cell interaction, we examined the effects of a subcutaneously injected therapeutic dose of insulin (0.15 U/kg) on plasma glucose kinetics, rates of glucose production and utilization, and their relationships to changes in the circulating concentrations of neuroendocrine glucoregulatory factors (glucagon, epinephrine, norepinephrine, growth hormone, and cortisol), as well as to changes in endogenous insulin secretion in 13 nonobese NIDDM patients with no clinical evidence of autonomic neuropathy. Compared with 11 age-weight matched nondiabetic volunteers in whom euglycemia was restored primarily by a compensatory increase in glucose production, in the diabetics there was no compensatory increase in glucose production (basal 2.08 +/- 0.04----1.79 +/- 0.07 mg/kg per min at 21/2 h in diabetics vs. basal 2.06 +/- 0.04----2.32 +/- 0.11 mg/kg per min at 21/2 h in nondiabetics, P less than 0.01) despite the fact that plasma insulin concentrations were similar in both groups (peak values 22 +/- 2 vs. 23 +/- 2 microU/ml in diabetics and nondiabetics, respectively). This abnormality in glucose production was nearly completely compensated for by a paradoxical decrease in glucose utilization after injection of insulin (basal 2.11 +/- 0.03----1.86 +/- 0.06 mg/kg per min at 21/2 h in diabetics vs. basal 2.08 +/- 0.04----2.39 +/- 0.11 mg/kg per min at 21/2 h nondiabetics, P less than 0.01), which could not be accounted for by differences in plasma glucose concentrations; the net result was a modest prolongation of hypoglycemia. Plasma glucagon (area under the curve [AUC] above base line, 12 +/- 3 vs. 23 +/- 3 mg/ml X 12 h in nondiabetics, P less than 0.05), cortisol (AUC 2.2 +/- 0.5 vs. 4.0 +/- 0.7 mg/dl X 12 h in nondiabetics, P less than 0.05), and growth hormone (AUC 1.6 +/- 0.4 vs. 2.9 +/- 0.4 micrograms/ml X 12 h in nondiabetics, P less than 0.05) responses in the diabetics were decreased 50% while their plasma norepinephrine responses (AUC 49 +/- 12 vs. 21 +/- 5 ng/ml X 12 h in nondiabetics, P less than 0.05) were increased twofold (P less than 0.05) and their plasma epinephrine responses were similar to those of the nondiabetics (AUC 106 +/- 17 vs. 112 +/- 10 ng/ml X 12 h in nondiabetics). In both groups of subjects, increases in plasma glucagon were inversely correlated with plasma glucose concentrations (r = -0.80 in both groups, P less than 0.01) and suppression of endogenous insulin secretion (r = -0.57 in nondiabe