The associates of gout-obesity, hypertriglyceridemia, glucose intolerance, and hypertension, strikingly resemble those of insulin resistance. In the present study we determined whether hyperuricemia is associated with insulin resistance and, if so, whether this association can be explained by other components of the syndrome. For this purpose we quantitated insulin sensitivity (euglycemic clamp) in 37 nondiabetic subjects (aged 30-68 yr) exhibiting varying degrees of the metabolic syndrome (body mass index, 21.5-35.7 kg/m2; serum triglycerides, 0.4-22.0 mmol/L; high density lipoprotein cholesterol 0.38-1.86 mmol/L; blood pressure, 190-100/116-60 mm Hg). In simple linear regression analysis, the serum uric acid concentration (range, 182-568 mumol/L) was inversely correlated with insulin sensitivity (rate of glucose utilization; r = -0.61; P < 0.001) and positively with serum triglycerides (r = 0.68; P < 0.001), but not with body mass index, age, or the plasma glucose concentration. In multiple linear regression analysis, both insulin sensitivity (P < 0.05) and serum triglycerides (P < 0.005) were independently associated with the serum uric acid concentration, and together explained 50% of its variation. Addition of body mass index or age to the model did not improve the degree of explanation. Acute elevation of serum triglycerides about 3-fold, of plasma FFA about 9-fold, or of serum insulin about 28-fold had no effect on the serum uric acid concentration in healthy volunteers. The data indicate that hyperuricemia is indeed an inherent component of the metabolic syndrome and could also be used as a simple marker of insulin resistance.

The associates of gout-obesity, hypertriglyceridemia, glucose intolerance, and hypertension, strikingly resemble those of insulin resistance. In the present study we determined whether hyperuricemia is associated with insulin resistance and, if so, whether this association can be explained by other components of the syndrome. For this purpose we quantitated insulin sensitivity (euglycemic clamp) in 37 nondiabetic subjects (aged 30-68 yr) exhibiting varying degrees of the metabolic syndrome (body mass index, 21.5-35.7 kg/m2; serum triglycerides, 0.4-22.0 mmol/L; high density lipoprotein cholesterol 0.38-1.86 mmol/L; blood pressure, 190-100/116-60 mm Hg). In simple linear regression analysis, the serum uric acid concentration (range, 182-568 mumol/L) was inversely correlated with insulin sensitivity (rate of glucose utilization; r = -0.61; P < 0.001) and positively with serum triglycerides (r = 0.68; P < 0.001), but not with body mass index, age, or the plasma glucose concentration. In multiple linear regression analysis, both insulin sensitivity (P < 0.05) and serum triglycerides (P < 0.005) were independently associated with the serum uric acid concentration, and together explained 50% of its variation. Addition of body mass index or age to the model did not improve the degree of explanation. Acute elevation of serum triglycerides about 3-fold, of plasma FFA about 9-fold, or of serum insulin about 28-fold had no effect on the serum uric acid concentration in healthy volunteers. The data indicate that hyperuricemia is indeed an inherent component of the metabolic syndrome and could also be used as a simple marker of insulin resistance.

Background-Coronary artery disease, an inflammatory disease, may be caused by infection. We investigated whether the antibiotic clarithromycin would reduce morbidity and mortality in patients with acute non-Q-wave coronary syndrome. Methods and Results-Altogether, 148 patients with acute non-Q-wave infarction or unstable angina were randomly assigned to receive double-blind treatment with either clarithromycin or placebo for 3 months. The primary end point was a composite of death, myocardial infarction, or unstable angina during treatment; the secondary end point was occurrence of any cardiovascular event during the entire follow-up period (average 555 days, range 138 to 924 days).There was a trend toward fewer patients meeting primary end-point criteria in the clarithromycin group than in the placebo group (11 versus 19 patients, respectively; risk ratio 0.54, 95% CI 0.25 to 1.14; Pϭ0.10). By the end of the entire follow-up, 16 patients in the clarithromycin group and 27 in the placebo group had experienced a cardiovascular event (risk ratio 0.49, 95% CI 0.26 to 0.92; Pϭ0.03). Conclusions-Clarithromycin appears to reduce the risk of ischemic cardiovascular events in patients presenting with acute non-Q-wave infarction or unstable angina. No signs of this effect diminishing were observed during follow-up.

To examine the mechanisms of hyperglycemia-induced insulin resistance, eight insulin-dependent (type I) diabetic men were studied twice, after 24 h of hyperglycemia (mean blood glucose 20.0 +/- 0.3 mM, i.v. glucose) and after 24 h of normoglycemia (7.1 +/- 0.4 mM, saline) while receiving identical diets and insulin doses. Whole-body and forearm glucose uptake were determined during a 300-min insulin infusion (serum free insulin 359 +/- 22 and 373 +/- 29 pM, after hyper- and normoglycemia, respectively). Muscle biopsies were taken before and at the end of the 300-min insulin infusion. Plasma glucose levels were maintained constant during the 300-min period by keeping glucose for 150 min at 16.7 +/- 0.1 mM after 24-h hyperglycemia and increasing it to 16.5 +/- 0.1 mM after normoglycemia and by allowing it thereafter to decrease in both studies to normoglycemia. During the normoglycemic period (240-300 min), total glucose uptake (25.0 +/- 2.8 vs. 33.8 +/- 3.9 mumol.kg-1 body wt.min-1, P less than 0.05) was 26% lower, forearm glucose uptake (11 +/- 4 vs. 18 +/- 3 mumol.kg-1 forearm.min-1, P less than 0.05) was 35% lower, and nonoxidative glucose disposal (8.9 +/- 2.2 vs. 19.4 +/- 3.3 mumol.kg-1 body wt-1min-1, P less than 0.01) was 54% lower after 24 h of hyper- and normoglycemia, respectively. Glucose oxidation rates were similar. Basal muscle glycogen content was similar after 24 h of hyperglycemia (234 +/- 23 mmol/kg dry muscle) and normoglycemia (238 +/- 22 mmol/kg dry muscle). Insulin increased muscle glycogen to 273 +/- 22 mmol/kg dry muscle after 24 h of hyperglycemia and to 296 +/- 33 mmol/kg dry muscle after normoglycemia (P less than 0.05 vs. 0 min for both). Muscle ATP, free glucose, glucose-6-phosphate, and fructose-6-phosphate concentrations were similar after both 24-h treatment periods and did not change in response to insulin. We conclude that a marked decrease in whole-body, muscle, and nonoxidative glucose disposal can be induced by hyperglycemia alone.

Acute physical exercise enhances insulin sensitivity in healthy subjects. We examined the effect of a 42-km marathon run on insulin sensitivity and lipid oxidation in 19 male runners. In the morning after the marathon run, basal serum free fatty acid concentration was 2.2-fold higher, muscle glycogen content 37% lower (P < 0.01), glycogen synthase fractional activity 56% greater (P < 0.01), and glucose oxidation reduced by 43% (P < 0.01), whereas lipid oxidation was increased by 55% (P < 0.02) compared with the control study. During euglycemic-hyperinsulinemic clamp, whole body glucose disposal was decreased by 12% (P < 0.01) because of a 36% lower glucose oxidation rate (P < 0.05), whereas the rate of lipid oxidation was 10-fold greater (P < 0.02) than in the control study. After the marathon, muscle glycogen content correlated positively with lipid oxidation (r = 0.60, P < 0.05) and maximal aerobic power (Vo2peak; r = 0.61, P < 0.05). Vo2peak correlated positively with basal lipid oxidation (r = 0.57, P < 0.05). In conclusion, 1) after the marathon run, probably because of increased lipid oxidation, the insulin-stimulated glucose disposal is decreased despite muscle glycogen depletion and the activation of glycogen synthase; 2) the contribution of lipid oxidation in energy expenditure is increased in proportion to physical fitness; 3) these adaptations of fuel homeostasis may contribute to the maintenance of physical performance after prolonged exercise.