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The prevalence of insulin resistance in the most common metabolic disorders is still an undefined issue. We assessed the prevalence rates of insulin resistance in subjects with impaired glucose tolerance (IGT), NIDDM, dyslipidemia, hyperuricemia, and hypertension as identified within the frame of the Bruneck Study. The study comprised an age- and sex-stratified random sample of the general population (n = 888; aged 40-79 years). Insulin resistance was estimated by homeostasis model assessment (HOMA(IR)), preliminarily validated against a euglycemic-hyperinsulinemic clamp in 85 subjects. The lower limit of the top quintile of HOMA(IR) distribution (i.e., 2.77) in nonobese subjects with no metabolic disorders (n = 225) was chosen as the threshold for insulin resistance. The prevalence of insulin resistance was 65.9% in IGT subjects, 83.9% in NIDDM subjects, 53.5% in hypercholesterolemia subjects, 84.2% in hypertriglyceridemia subjects, 88.1% in subjects with low HDL cholesterol, 62.8% in hyperuricemia subjects, and 58.0% in hypertension subjects. The prevalence of insulin resistance in subjects with the combination of glucose intolerance (IGT or NIDDM), dyslipidemia (hypercholesterolemia and/or hypertriglyceridemia and/or low HDL cholesterol), hyperuricemia, and hypertension (n = 21) was 95.2%. In isolated hypercholesterolemia, hypertension, or hyperuricemia, prevalence rates of insulin resistance were not higher than that in nonobese normal subjects. An appreciable number of subjects (n = 85, 9.6% of the whole population) was insulin resistant but free of IGT, NIDDM, dyslipidemia, hyperuricemia, and hypertension. These results from a population-based study documented that 1) in hypertriglyceridemia and a low HDL cholesterol state, insulin resistance is as common as in NIDDM, whereas it is less frequent in hypercholesterolemia, hyperuricemia, and hypertension; 2) the vast majority of subjects with multiple metabolic disorders are insulin resistant; 3) in isolated hypercholesterolemia, hyperuricemia, or hypertension, insulin resistance is not more frequent than can be expected by chance alone; and 4) in the general population, insulin resistance can be found even in the absence of any major metabolic disorders. [ABSTRACT FROM AUTHOR]

Background: Pregnancy strongly influences the thyroid gland and its function. Thyroid guidelines recommend a 30 to 50% increase of the preconceptional levothyroxine dose in women with hypothyroidism, when pregnancy is diagnosed., Case: A 33 year-old, 8-week pregnant woman with hypothyroidism, presents with a 2-week history of palpitations, sweating, nervousness and fatigue. Physical examination shows tachycardia (108 bpm), distal tremors and diffuse goiter. After biochemical confirmation of hyperthyroidism, her levothyroxine dose is reduced and finally interrupted. Propylthiouracil is started and maintained until after the delivery of a healthy baby at week 40. Two weeks postpartum, hyperthyroidism worsens and propylthiouracil is replaced by methimazole. Eighteen months after delivery 7.5 mCi 131Iodine was given. Two months later, hypothyroidism developed and levothyroxine was initiated., Conclusion: Although conversion of Hashimoto's hypothyroidism into Graves' disease is exceptional in pregnancy, pregnant women with autoimmune hypothyroidism should ideally have their TSH concentrations measured before empirically increasing their levothyroxine dose.

Background and Aim: Several working definitions of metabolic syndrome have been proposed for clinical use. However, individuals can be discordantly classified as having or not having metabolic syndrome depending on the choice of one or another definition. This study compared the cardiovascular risk profile of subjects concordantly and discordantly diagnosed by the criteria of the National Cholesterol Education Program (NCEP) and the criteria of the International Diabetes Federation (IDF)., Methods and Results: Nine hundred and twenty-nine non-diabetic adult subjects belonging to a cross-sectional population-based study in Gran Canaria island (Spain) were assessed. Participants completed a questionnaire and underwent physical examination, fasting blood analyses, and a standardized oral glucose tolerance test. Two hundred and four subjects (22%) had metabolic syndrome according to both definitions, 31 (3.3%) only by the IDF criteria, and 5 (0.5%) only by the NCEP criteria. Participants fulfilling both proposals showed more adverse age and sex-adjusted measures of BMI, waist, HDL cholesterol, triglycerides, post-load glucose, HOMA-IR and plasminogen inhibitor activator-1 (PAI-1) than individuals exclusively satisfying the IDF criteria. Moreover, in contrast to subjects meeting both criteria, those that fulfilled only the IDF criteria had levels of BMI, waist, total and HDL cholesterol, post-load glucose, glycated HbA1c, C-reactive protein, PAI-1 and fibrinogen not significantly different from those observed in subjects without metabolic syndrome., Conclusion: The IDF definition identifies a surplus of individuals whose cardiovascular risk profile, particularly regarding to some non-traditional cardiovascular risk factors, is less adverse than that observed in subjects also diagnosed by the NCEP definition.

The aim of this study was to ascertain whether the presence of hypertension conveys a more severe degree of insulin resistance in type 2 diabetes mellitus and, if so, which biochemical pathways are involved. We quantitated the rates of total glucose disposal, glycogen synthesis (GS), glycolysis, glucose oxidation, endogenous glucose production, and LOX in the basal state and during a 4-h euglycemic ( approximately 5 mM) hyperinsulinemic ( approximately 300 pM) clamp carried out in combination with a dual-tracer infusion ([(3)H]-3- and [(14)C]-U-D-glucose) and indirect calorimetry in 42 nonobese noninsulin-treated type 2 diabetic subjects (22 hypertensive and 20 normotensive) and 23 nonobese nondiabetic subjects (9 without and 14 with essential hypertension). Compared with normotensive controls, both groups of diabetic subjects were markedly insulin resistant. In the basal state, all glucose fluxes were similar in diabetic subjects with or without hypertension. During insulin infusion, total glucose disposal was significantly reduced in hypertensive diabetic subjects, compared with their normotensive counterparts (18.7 +/- 1.0 vs. 28.6 +/- 3.0 micromol/min.kg lean body mass; P < 0.01). This difference was almost entirely explained by a marked reduction in GS (4.5 +/- 2.0 vs. 12.5 +/- 3.3 micromol/min.kg lean body mass; P < 0.01). Endogenous glucose production was not different in the two diabetic groups during insulin infusion and was significantly higher than in normotensive controls. Lipid oxidation was less suppressed by hyperinsulinemia in hypertensive than in normotensive diabetic subjects (1.46 +/- 0.1 vs. 0.91 +/- 0.1 micromol/min.kg lean body mass; P < 0.01). Glucose fluxes were not significantly different in nondiabetic subjects with essential hypertension and in normotensive diabetic individuals. These results indicate that hypertension markedly aggravates insulin resistance featuring type 2 diabetes mellitus. The molecular defects underlying this phenomenon involve primarily GS.

Antihypertensive treatment is frequently needed in type 2 diabetes. In this study we measured the rates of total, oxidative, and nonoxidative glucose disposal, glycogen synthesis, glycolysis, endogenous glucose production, and lipid oxidation using a 4-h euglycemic (approximately 5 mmol/L) hyperinsulinemic (approximately 300 pmol/L) clamp in combination with a dual glucose tracer infusion ([3-(3)H]- and [U-14C] D-glucose) and indirect calorimetry in 40 nonobese subjects with type 2 diabetes. Subjects were studied twice: after a 4-week run-in period and after a 16-week period of double blind, randomized treatment with 4-6 mg/day lacidipine, a calcium channel blocker (n = 19), or 10-20 mg/day lisinopril, an angiotensin-converting enzyme inhibitor (n = 21). Antihypertensive treatment resulted in a significant increase in total glucose disposal during insulin clamp as well as in basal and insulin-stimulated nonoxidative glucose disposal rates. On the contrary, oxidative glucose disposal was significantly decreased by antihypertensive treatment, mainly in the basal state. The changes in glucose disposal rates were not significantly different in subjects treated with lacidipine and in those treated with lisinopril. The suppression of endogenous glucose production during insulin clamp was significantly greater after lacidipine than after lisinopril. These results suggest that treatment of subjects with type 2 diabetes with either lacidipine or lisinopril has no adverse effect on glucose metabolism. Conversely, both drugs seem to improve insulin sensitivity.