Comparison of the Associations of Apolipoprotein B and Low-Density Lipoprotein Cholesterol With Other Cardiovascular Risk Factors in the Insulin Resistance Atherosclerosis Study (IRAS)

Background— Risk factors for vascular disease include obesity, dyslipidemia, hypertension, dysglycemia, insulin resistance, inflammation, thrombosis, and subclinical atherosclerosis. This study compares the associations of apolipoprotein B (apoB) and LDL cholesterol (LDLC) with a wide array of measures of these risk factors.

Methods and Results— In 1522 individuals in the Insulin Resistance Atherosclerosis Study, anthropometric measures and measures of lipids, apoB, C-reactive protein, fibrinogen, plasminogen activator inhibitor-1 (PAI-1), fasting and postglucose load glucose and insulin concentrations, and carotid artery intima-media thickness (IMT) were taken and insulin sensitivity was determined by frequently sampled intravenous glucose tolerance test. There were significant differences in measures of abdominal obesity, dyslipidemia, hyperinsulinemia, and thrombosis between subjects with elevated apoB but normal LDLC versus those with elevated LDLC but normal apoB. In each statistically significant comparison, the elevated-apoB group had higher associated risk than the elevated-LDLC group. Moreover, apoB is highly significantly ( P <0.0001) correlated with each measure in the direction of higher risk, whereas LDLC was significantly correlated ( P <0.05) only with blood pressure, triglyceride, fibrinogen, and C-reactive protein. After further adjustment for LDLC, apoB correlations remained significant, whereas several LDLC correlations adjusted for apoB became significant in the direction of lower risk.

Conclusions— Elevated apoB is more strongly associated than LDLC with other risk factors, including measures in the National Cholesterol Education Program guidelines for lipid treatment and other more recently established risk factors. This may provide new insight into why apoB is a better predictor of vascular risk than LDLC.

Long-Term (2???4 Year) Weight Reduction With Metformin Plus Carbohydrate-Modified Diet in Euglycemic, Hyperinsulinemic, Midlife Women (Syndrome W)

Long-term weight reduction remains the ultimate objective and challenge of obesity management. Few long-term dietary or pharmacointervention studies have been conducted and there is a critical need for long-range treatment strategies that are effective, safe, and acceptable. The authors conducted a retrospective cohort analysis of 21 euglycemic, hyperinsulinemic women with progressive, refractory, midlife weight gain (Syndrome W) who had previously lost weight (> or =10% reduction from baseline) with a comprehensive 1-year treatment program that included metformin and a hypocaloric, carbohydrate-modified (low-glycemic index) diet, as well as, other lifestyle modifications. The goal of the analysis was to determine long-term efficacy of the composite intervention using NHLBI criteria for weight stabilization, weight regain < or =3 kg (6.6 lb) in 2 years. Of a total of 26 consecutive women with Syndrome W who achieved goal weight during a 3-year period (1998-2001), 21 women (mean [standard error] age, 55.2 [2.4] years; mean body mass index, 34.2 [1.3] kg/m(2)) continued metformin and returned for annual follow-up visits. Weight maintenance was observed at the final (2-4 year) follow-up visit in 19/21 (90.5%) of women. Mean final follow-up weight (77.5 [2.8] kg) correlated highly with mean weight at 1-year protocol completion (77.2 [2.7] kg), (correlation coefficients r(xy) and sigma(xy) = 0.96, P = 0.000), demonstrating long-term weight reduction in the surveillance phase. Significant and robust decrements in fasting insulin (-28.4% [8.1%] to -43.4% [3.7%]) were observed at all follow-up visits (P < or = 0.002). This preliminary case series suggests that metformin may be an effective long-term adjunct to dietary and other interventions in the treatment of obesity in hyperinsulinemic patients. A randomized clinical trial of the dual regimen should be considered in nondiabetic women with midlife weight gain and hyperinsulinemia (Syndrome W) and, quite possibly, in additional euglycemic overweight and obese subjects with documented hyperinsulinemia and other portentous features of the Metabolic Syndrome.

[The role of ischemic heart disease risk factors in pathogenesis of cardiological syndrome X]

To specify lipid and carbohydrate metabolisms, coagulation and platelet hemostasis and their relationships with impairment of coronary circulation in patients with cardiological syndrome X (SX), we examined 204 SX patients and 31 controls. Compared to the controls, examinees with SX had signs of hyperinsulinemia, high levels of LDLP cholesterol, VLDLP cholesterol, atherogenic index, packed cell volume, fibrinogen and platelet aggregation. We found a positive correlation between the level of LDLP cholesterol, severity of hyperinsulinemia and maximal depression of ST wave in the course of bicycle exercise. There was no correlation between hemostasis parameters and the degree of ST depression.

Persistent hyperinsulinemic hypoglycemia of infancy in 38 children

OBJECTIVE

To describe the clinical, biochemical, radiological and electrophysiological features of 38 Saudi children with persistent hyperinsulinemic hypoglycemia of infancy that have been followed since 1983.

METHODS

Data from 38 patients followed at King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia from 1983 through to 2002 was retrospectively analyzed. Persistent hyperinsulinemic hypoglycemia of infancy was diagnosed on the basis of high intravenous glucose requirement, high insulin to glucose ratio, negative urinary ketones and normal tandem mass spectrometry. The patients were assessed radiologically by brain magnetic resonance imaging, computed tomography, or both and electrophysiologically by brain stem auditory evoked potential, visual evoked response and electroencephalogram. The patients who failed medical therapy had subtotal pancreatectomy.

RESULTS

The patients were severely hypoglycemic and intolerant to fast. Hypoglycemic convulsion was the most commonly presenting complaint. Eighteen patients were developmentally delayed and 14 of them had brain atrophy. All patients, except nine, did not respond to medical treatment and had surgery. Four pancreatectomized patients developed diabetes and 2 had malabsorption. One patient was treated medically during childhood and developed diabetes and weight gain during adolescence.

CONCLUSION

Persistent hyperinsulinemic hypoglycemia of infancy is a relatively common and serious disease among Saudi children. Early medical intervention is necessary to avoid neurological damage in our patients who are severely hypoglycemic and medical therapy unresponsive. Surgically and probably medically treated patients are at high risk of developing diabetes that could be the natural outcome of this disease.

Screening for metabolic syndrome in hypertensive and/or obese subjects registered in primary health care in Hungary

BACKGROUND

The screening of subjects at risk for metabolic syndrome is of considerable importance in order to prevent atherosclerosis.

MATERIAL/METHODS

In order to assess the clinical-laboratory characteristics of metabolic syndrome,a screening procedure was performed in subjects (age 20 -65)who exhibited hypertension and/or abnormal body mass index (BMI)and/or elevated waist-hip ratio,excluding patients with known diabetes. An oral glucose tolerance test with 75 g glucose was performed. Plasma glucose and insulin values were measured,as well as plasma lipids.

RESULTS

In subjects available for complete statistical analysis (n=944;women/men ratio 1.37:1),hyperinsulinemia was detected in 52.9%. Hyperinsulinemia with normal glucose tolerance was more often detected (33.2%),hyperinsulinemia with impaired glucose tolerance [IGT ]or diabetes less frequently (13.0%and 6.7%,respectively). When abnormal clinical signs were separately analysed,hyperinsulinemia was found in 56.8%of subjects with abnormal BMI,in 43.8% of subjects with abnormal waist-hip ratio,and in 27.1% of subjects with hypertension. Metabolic syndrome (WHO criteria,modified)was diagnosed in 35.2%of subjects,with male predominance (men:40.6%;women:31.2%;p<0.01).

CONCLUSIONS

Obesity (abnormal BMI;abnormal waist-hip ratio)is of greater importance than hypertension alone for detecting subjects with hyperinsulinemia.Routine clinical and laboratory investigations (anthropometric data,measuring blood pressure,oral glucose tolerance test)are simple but useful for identifying subjects with metabolic syndrome,enabling the implementation of a primary strategy to prevent cardiovascular morbidity.

Development of insulin resistance and endothelin-1 levels in the Zucker fatty rat

In order to determine the effects of increasing insulin resistance on endothelin-1 (ET-1) levels, Zucker lean and fatty rats were studied at basal and during a complete nutrient meal tolerance test (MTT) at 7, 12, and 15 weeks of age. The fatty rats were mildly hyperglycemic, severely hyperinsulinemic and glucose-intolerant at all ages versus lean animals and this progressed with age within groups, as previously published. Basal ET-1 levels, at 7 weeks, were significantly increased in fatty versus lean rats (3.2+/-0.5 v 2.0+/-0.3 pg/mL, respectively; P<.05); however, we did not observe any significant basal difference at 12 or 15 weeks. At 7 weeks, ET-1 levels between fatty and lean rats were not different during the MTT (15 minutes: 2.9+/-0.4 v 2.7+/-0.7; 120 minutes: 6.5+/-0.8 v 6.6+/-0.5 pg/mL, fatty v lean, respectively). At 12 weeks, though there was no difference in basal levels, fatty rats had higher ET-1 levels during the MTT compared to lean animals (15 minutes: 6.9+/-1.4 v 1.8+/-0.4; 120 minutes: 9.4+/-1.7 v 3.2+/-0.5 pg/mL, respectively; P<.01). At 15 weeks, ET-1 levels during the MTT receded to levels similar to those observed at 7 weeks, which were significantly higher in fatty versus lean rats 15 minutes following the challenge (3.4+/-0.4 v 2.4+/-0.2 pg/mL, respectively; P<.05). In conclusion, ET-1 levels in the Zucker fatty rat: (1) were increased in the early stages of the progression of insulin resistance at 7 weeks, but were unchanged under basal conditions with age thereafter, and (2) were increased under nutrient challenge conditions with advanced insulin resistance up to 12 weeks, and were still significantly but to a lesser degree increased at 15 weeks of age. The explanation for these results and their relationship to the observed insulin resistance is unclear and will require further investigation.

Long-term follow-up of 114 patients with congenital hyperinsulinism

BACKGROUND

The term congenital hyperinsulinism (CHI) comprises a group of different genetic disorders with the common finding of recurrent episodes of hyperinsulinemic hypoglycemia.

OBJECTIVE

To evaluate the clinical presentation, diagnostic criteria, treatment and long-term follow-up in a large cohort of CHI patients.

PATIENTS

The data from 114 patients from different hospitals were obtained by a detailed questionnaire. Patients presented neonatally (65%), during infancy (28%) or during childhood (7%).

RESULTS

In 20 of 74 (27%) patients with neonatal onset birth weight was greatly increased (group with standard deviation scores (SDS) >2.0) with a mean SDS of 3.2. Twenty-nine percent of neonatal-onset vs 69% of infancy/childhood-onset patients responded to diazoxide and diet or to a carbohydrate-enriched diet alone. Therefore, we observed a high rate of pancreatic surgery performed in the neonatal-onset group (70%) compared with the infancy/childhood-onset group (28%). Partial (3%), subtotal (37%) or near total (15%) pancreatectomy was performed. After pancreatic surgery there appeared a high risk of persistent hypoglycemia (40%). Immediately post-surgery or with a latency of several Years insulin-dependent diabetes mellitus was observed in operated patients (27%). General outcome was poor with a high degree of psychomotor or mental retardation (44%) or epilepsy (25%). An unfavorable outcome correlated with infancy-onset manifestation (chi(2)=6.1, P=0.01).

CONCLUSIONS

The high degree of developmental delay, in particular in infancy-onset patients emphasizes the need for a change in treatment strategies to improve the unfavorable outcome. Evaluation of treatment alternatives should take the high risk of developing diabetes mellitus into account.

[The incidence of hyperinsulinemia in patients with tinnitus and the effect of a diabetic diet on tinnitus]

OBJECTIVES

We investigated the incidence of hyperinsulinemia in patients presenting with tinnitus and evaluated the effect of diabetic diet on tinnitus.

PATIENTS AND METHODS

Serum insulin levels were measured and oral glucose tolerance test was performed in 52 patients (26 males, 26 females; mean age 50 years; range 20 to 80 years) with idiopathic tinnitus. Those with hyperinsulinemia were given a diabetic diet for four months. A questionnaire was administered to all the patients and the complaint of tinnitus was assessed according to a rating scale before and after treatment. The results were compared with those of 15 age-and sex-matched controls.

RESULTS

Hyperinsulinemia was detected in 76% and 27% of the patients and the controls, respectively (p<0.05). Oral glucose tolerance test was normal in 48% of the patients, and in 80% of the controls (p<0.05). Following a diabetic diet, the severity of tinnitus complaints significantly decreased in patients with hyperinsulinemia (p<0.0001).

CONCLUSION

Hyperinsulinemia may play an etiologic role in tinnitus and a diabetic diet may result in significant improvement in tinnitus complaints in this population.

Role of salt sensitivity, blood pressure, and hyperinsulinemia in determining high upper normal levels of urinary albumin excretion in a healthy adult population

BACKGROUND

The objective of this study was to investigate the role of blood pressure (BP), salt sensitivity (SS), and the cardiovascular metabolic syndrome in determining the urinary albumin excretion (UAE) in glucose-tolerant, normoalbuminuric (<20 mg/day) healthy adults.

METHODS AND RESULTS

We evaluated 177 healthy subjects (age, 38.3 +/- 0.9 years; weight, 75.2 +/- 1.1 kg; body mass index, 28.8 +/- 0.4 kg/m(2); systolic BP, 117 +/- 1 mm Hg; diastolic BP, 77.5 +/- 0.8 mm Hg; UAE, 8.2 +/- 0.3 mg/24 h). Subjects with UAE levels of 15 to 20 mg/day had higher systolic BP, diastolic BP, and pulse pressures than those with UAE levels less than 15 mg/day (P <.0001). Hypertension (HT) and SS were more prevalent in the high normal UAE group (15 to 20 mg/day) than in groups with lower UAE (47% v 8% for HT and 67% v 24% for SS). In normotensives (n = 156), no differences in BP were observed among the different UAE strata; yet, the prevalence of SS was greater in the high (57%) compared to the low normal (17% to 21%) UAE groups. Similar levels of UAE, BP, and similar prevalence of SS were found in men with and without abdominal obesity, despite the fact that obesity was associated with hypertriglyceridemia and hyperinsulinemia.

CONCLUSIONS

In healthy normoalbuminuric adults, high normal UAE is associated with SS in normotensives and with SS and higher BP in a mixed population (88% normotensive and 12% hypertensive). Abdominal obesity, hypertriglyceridemia, and hyperinsulinemia were not related to UAE. Therefore, UAE levels of 15 to 20 mg/day should be accepted as microalbuminuria, and these subjects may benefit from early intervention (ie, salt restriction and BP lowering).

C-reactive protein is independently associated with fasting insulin in nondiabetic women

OBJECTIVE

Insulin resistance is associated with chronic subclinical inflammation, and both conditions are linked with increased risk for type 2 diabetes mellitus and atherothrombotic cardiovascular disease.

METHODS AND RESULTS

In a cross-sectional study conducted among participants in the Women's Health Study, an ongoing US primary prevention trial of cardiovascular disease and cancer, we evaluated the correlates of elevated fasting insulin, a marker of insulin resistance, among 349 healthy, nondiabetic women who remained free from clinically diagnosed type 2 diabetes mellitus during a 4-year period from biomarker assessment. Fasting insulin was strongly associated with body mass index (BMI) (r=0.53, P<0.001), C-reactive protein (CRP) (r=0.38, P<0.001), and interleukin-6 (r=0.33, P<0.001). Physical activity level, alcohol consumption, and use of hormone replacement therapy were also related to fasting insulin. However, in multivariable linear regression analysis, BMI and CRP were the only independent correlates of log-normalized fasting insulin. Overall, the final model explained 32% of the variance in log insulin level. In multivariable logistic regression, the fully adjusted odds ratio (OR) for elevated fasting insulin (>or=51.6 pmol/L) increased with tertile of BMI, CRP, and IL-6, such that the ORs in the highest versus lowest tertile of each parameter were 9.0 (95% confidence interval [CI], 4.4 to 18.7), 4.4 (95% CI, 1.9 to 10.1), and 2.0 (95% CI, 0.9 to 4.2), respectively. Furthermore, increasing levels of CRP were associated with a stepwise gradient in odds for elevated fasting insulin among both lean and overweight women.

CONCLUSIONS

CRP is independently associated with fasting hyperinsulinemia in nondiabetic women. These data provide additional support for previously reported associations between subclinical inflammation and the risk of type 2 diabetes and cardiovascular disease.

Association between weight fluctuation and fasting insulin concentration in Japanese men

OBJECTIVE

To investigate whether long-term weight fluctuation is associated with the fasting serum insulin concentration.

DESIGN AND SUBJECTS

Weight histories of 1932 male Japanese workers aged 40-59 y were analyzed in relation to their current fasting serum insulin concentration.

MEASUREMENTS

Individual weight fluctuation was calculated by root mean square error (RMSE) along the linear regression line of weight measured at five to six different ages.

RESULTS

The mean RMSE and fasting insulin concentration were 1.22 kg and 4.5 microU/ml, respectively. The multivariate adjusted insulin level became higher with the increase in weight fluctuation. Subanalysis stratified by current body mass index (BMI) showed that the multivariate adjusted insulin level in individuals in the top quartile of fluctuation was 4.3 microU/ml, against 3.9 microU/ml in those in the bottom quartile (P=0.018, analysis of covariance (ANCOVA)) in the normal weight subgroup with current BMI below 25 kg/m(2). In the overweight subgroup with BMI 25 kg/m(2) or above, the level was 6.9 microU/ml in individuals in the top quartile and 6.2 microU/ml in those in the bottom quartile (P=0.054, ANCOVA).

CONCLUSION

The results suggest that weight fluctuation increases the risk of developing hyperinsulinemia. Prospective observations together with measurement of changes in adiposity are needed for confirmation.

[Prevalence of obesity and hyperinsulinemia: its association with serum lipid and lipoprotein concentrations in healthy individuals from Maracaibo, Venezuela]

The aim of this study was to analyse the prevalence of obesity and hyperinsulinemia and their association with lipid profile alterations on apparently healthy individuals from Maracaibo, Venezuela. We evaluated 306 men and 41 women, ages ranging from 33 to 65 years. All subjects underwent cardiovascular evaluation and laboratory examination after 10-12 h fasting, for glycaemia, total cholesterol, TG, VLDL-C, LDL-C and HDL-C as well as insulin. Seventy-four percent of men and 56.1% of women showed obesity (BMI > 25 Kg/m2). Men showed high concentrations of TG (48.3%), total cholesterol (40.2%), VLDL-C (48.3%) and LDL-C (33.9%) and low HDL-C levels (48%). The most frequent alteration on the lipid profile in women was high total cholesterol (46%) and LDL-C (51.2%). Men had significantly higher insulin concentrations than women (p < 0.005). After they were classified as obese or non obese, the obese subjects (men and women) showed higher prevalence of lipid profile alterations and insulin concentrations than non obese. The insulin concentration in obese men correlated with BMI, TG, VLDL-C and HDL and, in women with BMI, TG and VLDL-C. In conclusion, a high percentage of men and women in this study showed obesity and this obesity, specially in men, was strongly associated with lipid profile alterations and high insulin concentrations both well known cardiovascular risk factors.

Diabetes, plasma insulin, and cardiovascular disease: subgroup analysis from the Department of Veterans Affairs high-density lipoprotein intervention trial (VA-HIT)

BACKGROUND

Diabetes mellitus, impaired fasting glucose level, or insulin resistance are associated with increased risk of cardiovascular disease.

OBJECTIVES

To determine the efficacy of gemfibrozil in subjects with varying levels of glucose tolerance or hyperinsulinemia and to examine the association between diabetes status and glucose and insulin levels and risk of cardiovascular outcomes.

METHODS

Subgroup analyses from the Department of Veterans Affairs High-Density Lipoprotein Intervention Trial, a randomized controlled trial that enrolled 2531 men with coronary heart disease (CHD), a high-density lipoprotein cholesterol level of 40 mg/dL or less (</=1.04 mmol/L), and a low-density lipoprotein cholesterol level of 140 mg/dL or less (</=3.63 mmol/L). Subjects received either gemfibrozil (1200 mg/d) or matching placebo and were followed up for an average of 5.1 years. In this article, we report the composite end point (CHD death, stroke, or myocardial infarction).

RESULTS

Compared with those with a normal fasting glucose level, risk was increased in subjects with known diabetes (hazard ratio [HR], 1.87; 95% confidence interval [CI], 1.44-2.43; P =.001) and those with newly diagnosed diabetes (HR, 1.72; 95% CI, 1.10-2.68; P =.02). In persons without diabetes, a fasting plasma insulin level of 39 micro U/mL or greater (>/=271 pmol/L) was associated with a 31% increased risk of events (P =.03). Gemfibrozil was effective in persons with diabetes (risk reduction for composite end point, 32%; P =.004). The reduction in CHD death was 41% (HR, 0.59; 95% CI, 0.39-0.91; P =.02). Among individuals without diabetes, gemfibrozil was most efficacious for those in the highest fasting plasma insulin level quartile (risk reduction, 35%; P =.04).

CONCLUSION

In men with CHD and a low high-density lipoprotein cholesterol level, gemfibrozil use was associated with a reduction in major cardiovascular events in persons with diabetes and in nondiabetic subjects with a high fasting plasma insulin level.

Hypertension and insulin disorders

Insulin resistance and/or compensatory hyperinsulinemia are associated with hypertension, obesity, dyslipidemia, and glucose intolerance. Insulin resistance and hyperinsulinemia are considered to increase blood pressure through sympathetic nervous system activation, renin-angiotensin system stimulation, and vascular smooth muscle cell proliferation. Leptin, magnesium ions, nitric oxide, endothelin, peroxisome proliferator-activated receptor gamma, and tumor necrosis factor-alpha also modulate blood pressure. Decreasing insulin resistance by lifestyle modification including diet, weight loss, and physical exercise has been shown to reduce blood pressure. Angiotensin-converting enzyme inhibitors have a beneficial effect on insulin resistance. On the other hand, the angiotensin II antagonist, losartan, does not affect insulin sensitivity. The selective alpha1-blockers have a favorable metabolic profile producing increases in insulin sensitivity. A short-acting type calcium channel blocker seems to decrease insulin sensitivity. On the other hand, long-acting type calcium channel blockers improve insulin sensitivity. Thiazide diuretics and most of the beta-blockers decrease insulin sensitivity. Vasodilatory beta-blockers have been reported to improve insulin sensitivity. Use of low-dose diuretics avoids the adverse effects seen with conventional doses.

Frequency of the WHO metabolic syndrome in European cohorts, and an alternative definition of an insulin resistance syndrome

BACKGROUND

To describe the frequency, in some European populations, of the World Health Organisation (WHO) defined metabolic syndrome and to compare the frequency of this syndrome with an alternative definition for non-diabetic subjects, called the insulin resistance syndrome proposed by the European Group for the Study of Insulin Resistance (EGIR).

METHODS

Investigators of eight European studies contributed, according to a written protocol, the frequencies of abnormalities of these two syndromes, by sex and age class, as well as the overall frequencies of the syndromes and the average number of abnormalities: 8200 men and 9363 women were included.

RESULTS

The frequency of both syndromes increased with age and was almost always higher in men than women for a given age. In non-diabetic subjects the frequency of the WHO syndrome varied between 7% and 36% for men 40 to 55 years; for women of the same age, between 5% and 22%. The EGIR syndrome was less frequent than the WHO syndrome (1% to 22% in men, 1% to 14% in women 40-55 years), and in men this was mainly due to the differing definitions of central obesity, as the WHO definition included overall obesity, BMI > or = 30 kg/m(2).

CONCLUSIONS

There is great variability in the frequency of the syndrome between different populations, due to the differing frequencies of the abnormalities and no doubt to the differing methodologies of measurement. Prospective studies and advances in the knowledge of physio-pathological mechanisms are required to determine the most appropriate and practical definition of the syndrome.

Time-course of adiposity and fasting insulin from childhood to young adulthood in offspring of parents with coronary artery disease: the Bogalusa Heart Study

PURPOSE

Obesity and the attendant insulin resistance/hyperinsulinemia related to coronary artery disease (CAD) morbidity and mortality are well documented. However, information is lacking on the time-course relation of adiposity and fasting insulin from childhood to young adulthood in offspring of parents with CAD, a surrogate measure of future risk.

METHODS

Longitudinal analysis was performed on data collected from the Bogalusa Heart Study cohort with (n = 271) and without (n = 805) a parental history of CAD followed since childhood by repeated surveys from 1973 to 1991.

RESULTS

Lowess smoothing and multivariate analyses using Generalized Estimating Equations revealed that body mass index, triceps, and subscapular skinfolds were consistently higher from childhood to adulthood in offspring of parents with CAD history. Insulin levels during childhood and adolescence were lower in the offspring with affected parents. On the other hand, higher levels of fasting insulin from offspring were associated with positive parental history of CAD after age 20 and this association remained significant even after adjusting for body mass index. There was no significant interaction with race or sex in these relationships.

CONCLUSION

These results indicate that the offspring at high risk for CAD develop excess body fatness beginning in childhood and then later manifest hyperinsulinemia in young adulthood. These observations have important implications for prevention.

Risk factor groupings related to insulin resistance and their synergistic effects on subclinical atherosclerosis: the atherosclerosis risk in communities study

The extent to which groupings of insulin resistance-related cardiovascular risk factors synergize to produce atherosclerosis beyond what is expected from their additive effects is uncertain. The objective of this study was to measure interactions among groupings of the features of the insulin resistance syndrome (IRS) on carotid intimal-medial thickness (IMT). This cross-sectional study used baseline data from the Atherosclerosis Risk in Communities Study on 11,790 adults aged 45-64 years without diagnosed diabetes, treated dyslipidemia, or coronary heart disease. The main outcome was carotid IMT, assessed using B-mode ultrasound. The excess carotid IMT attributable to each IRS grouping was determined using multiple linear regression models. There were 57 possible combinations of six IRS components (hypertension, hyperinsulinemia, obesity, hypertriglyceridemia, low HDL cholesterol, and hyperglycemia). In multivariate analysis, 29 of the 57 groupings were associated with excess carotid IMT. Individuals with all six IRS components had the greatest excess IMT compared with those without this grouping (71 micro m; 95% CI 40-102 micro m). The groupings most strongly associated with excess carotid IMT included hypertension and hypertriglyceridemia. Interventions aimed at ameliorating the IRS may produce reductions in atherosclerotic risk beyond that predicted by treatment of individual IRS-related risk factors.

Components of the "metabolic syndrome" and incidence of type 2 diabetes

The combination of insulin resistance, dyslipidemia, hypertension, and obesity has been described as a "metabolic syndrome" that is a strong determinant of type 2 diabetes. Factor analysis was used to identify components of this syndrome in 1,918 Pima Indians. Prospective analyses were conducted to evaluate associations of identified factors with incidence of diabetes. Factor analysis identified 4 factors that accounted for 79% of the variance in the original 10 variables. Each of these factors reflected a proposed component of the metabolic syndrome: insulinemia, body size, blood pressure, and lipid metabolism. Among 890 originally nondiabetic participants with follow-up data, 144 developed diabetes in a median follow-up of 4.1 years. The insulinemia factor was strongly associated with diabetes incidence (incidence rate ratio [IRR] for a 1-SD difference in factor scores = 1.81, P < 0.01). The body size and lipids factors also significantly predicted diabetes (IRR 1.52 and 1.37, respectively, P < 0.01 for both), whereas the blood pressure factor did not (IRR 1.11, P = 0.20). Identification of four unique factors with different associations with incidence of diabetes suggests that the correlations among these variables reflect distinct metabolic processes, about which substantial information may be lost in the attempt to combine them into a single entity.

Relationship between hyperinsulinemia and angiographically defined coronary atherosclerosis in non-diabetic men

BACKGROUND

Our aim was to estimate the relationship between hyperinsulinemia and angiographically validated coronary atherosclerosis.

METHODS

102 consecutive non-diabetic male subjects (age 48.9 +/- 9.6 years) with a body mass index 25.9 +/- 2.8 kg/m(2) referred to coronary angiography in our centre were studied. A 75-g oral glucose tolerance test (OGTT) was performed and the areas under the curve (AUC) of serum insulin and glucose were calculated.

RESULTS

Discriminant analysis with stepwise forward variable selection revealed that in younger patients (<50 years), the following parameters affected positively the number of significant coronary lumen reductions: age (F=8.5, p=0.005), lnAUCinsulin (F=5.8, p=0.02), low HDL cholesterol (F=4.4, p=0.04), the smoking habit (F=4.1, p=0.05). In those >=50 years of age, exclusively age (F=5.8, p=0.02) and hyperuricemia (F=3.8, p=0.06) entered the final model.

CONCLUSION

Our results indicate that in non-diabetic male subjects the association of hyperinsulinemia with the severity of coronary atherosclerosis is only seen in younger patients.

Glucose and insulin responses in offspring of Nigerian Type 2 diabetics

Type 2 diabetes mellitus has a strong genetic basis by a concordance rate ranging between 60 and 90% in monozygotic twins. Glucose and insulin responses to an oral glucose load were measured in 52 offspring of Nigerian Type 2 diabetics and 50 control subjects selected to achieve a similar distribution of age and gender. All subject studied were glucose tolerant. In comparison with control subjects, offspring of Type 2 diabetics had a significantly higher mean (SD) (i) fasting plasma glucose level [69.2 (13.0) mg/dl vs. 62.2 (7.6) mg/dl; P = 0.0012] (ii) fasting plasma insulin level [26.6 (15.4) microIU/ml vs 14.8 (6.8) microIU/ml; P < 0.0001] (iii) 2 hours post glucose load plasma insulin level [59.8 (33.9) microIU/ml vs. 40.9 (24.2) microIU/ml; P = 0.0028]. The mean (SD) 2-hour post glucose load plasma glucose level did not differ significantly between both groups of subjects [92.8 (23.8) mg/dl vs. 85.5 (21.3) mg/dl; P = 0.11]. Further multiple regressional analysis showed that the differences in fasting plasma insulin and 2-hour post glucose load insulin observed were only accounted for by the presence of a parental history of diabetes and were not influenced significantly by BMI, waist and hip circumferences. This study shows that offspring of Nigerian Type 2 diabetics have hyperinsulinaemia, despite being glucose tolerant and this supports the insulin-resistance hypothesis for Type 2 DM. This implies that they are at a greater risk for developing diabetes mellitus and are therefore an important group for the primary prevention of Type 2 DM.

Management of nonalcoholic steatohepatitis: an analytic review

Nonalcoholic steatohepatitis (NASH) is a metabolic disorder of the liver, which, although usually relatively mild, may in some cause fibrosis, cirrhosis, and premature death resulting from liver failure. Its prevalence is increasing, and it is probably underestimated as a cause for cirrhosis. The need for an effective treatment is clear and urgent. Although several small, pilot, and randomized studies have been reported, large-scale studies are yet to be performed in patients with NASH. The aim of therapy is to intervene early in patients at risk of progression of liver disease. In this review, we summarize the extant literature on the management of NASH and discuss the potential future therapies and prophylactic recommendations in patients with NASH.

Obesity and weight gain are associated with increased incidence of hyperinsulinemia in non-diabetic men

We investigated the temporal relationships between obesity, weight change and hyperinsulinemia in a population-based 4-year follow-up study of 695 middle-aged, non-diabetic, and normoinsulinemic men. Thirty-eight men developed hyperinsulinemia during the follow-up (fasting serum insulin > or = 12.0 mU/l). In logistic regression analysis adjusting for other risk factors, men with body mass index of > or = 26.7 kg/m2 (highest third) had a 6.6-fold (p = 0.001) risk of developing hyperinsulinemia, compared with men with body mass index of < 24.4 kg/m2 (lowest third). Correspondingly, men with waist-to-hip ratio of > or = 0.95 (highest third) had a 3.5-fold (p = 0.028) incidence of hyperinsulinemia compared with men with waist-to-hip ratio of < 0.90 (lowest third). Weight gain in middle age and weight gain from the age of 20 years to middle age were also associated with increased risk of hyperinsulinemia. Hyperinsulinemia at baseline was not associated with weight gain during the follow-up. This prospective population-based study emphasizes the importance of avoiding obesity and weight gain during adulthood in preventing hyperinsulinemia.

Analysis of obesity and hyperinsulinemia in the development of metabolic syndrome: San Antonio Heart Study

OBJECTIVE

To use standardized cut-offs of body mass index (BMI), waist circumference, waist-to-hip ratio, and fasting insulin levels to predict the development of metabolic disorders and metabolic syndrome.

RESEARCH METHODS AND PROCEDURES

We performed an 8-year follow-up study of 628 non-Hispanic whites and 1340 Mexican Americans, ages 25 to 64 years, from the second cohort of the San Antonio Heart Study. We defined metabolic disorders as dyslipidemia (triglycerides > or =2.26 mM or high-density lipoprotein <0.91 mM in men and <1.17 mM in women), hypertension (blood pressure > or =140 or >=90 mm Hg, or receiving antihypertensive medications), and type 2 diabetes (fasting glucose > or =7.0 mM, 2-hour test glucose > or =11.1 mM, or receiving anti-diabetic medications). People with at least two metabolic disorders were defined as having metabolic syndrome.

RESULTS

High waist-to-hip ratio and fasting insulin levels were significant predictors of developing metabolic syndrome. High anthropometric indices remained significant predictors of metabolic syndrome after adjusting for fasting insulin. Waist circumference, BMI, and insulin had similar areas under the receiver operating characteristic curves (0.74 to 0.76). Further multivariate analyses combining these indices showed minimal increase in prediction. Of subjects who had a combination of high BMI (> or =30 kg/m(2)) and high waist circumference (above "Action Level 2"), 32% developed metabolic syndrome, compared with 10% of subjects with both low BMI and low waist circumference.

DISCUSSION

These findings support the National Institutes of Health recommendations for reducing the risk of metabolic syndrome. Adjustment for baseline fasting insulin levels had only a small effect on the ability of anthropometric indices to predict the metabolic syndrome.

K(ATP) channels and insulin secretion disorders

ATP-sensitive potassium (K(ATP)) channels are inhibited by intracellular ATP and activated by ADP. Nutrient oxidation in beta-cells leads to a rise in [ATP]-to-[ADP] ratios, which in turn leads to reduced K(ATP) channel activity, depolarization, voltage-dependent Ca(2+) channel activation, Ca(2+) entry, and exocytosis. Persistent hyperinsulinemic hypoglycemia of infancy (HI) is a genetic disorder characterized by dysregulated insulin secretion and, although rare, causes severe mental retardation and epilepsy if left untreated. The last five or six years have seen rapid advance in understanding the molecular basis of K(ATP) channel activity and the molecular genetics of HI. In the majority of cases for which a genotype has been uncovered, causal HI mutations are found in one or the other of the two genes, SUR1 and Kir6.2, that encode the K(ATP) channel. This article will review studies that have defined the link between channel activity and defective insulin release and will consider implications for future understanding of the mechanisms of control of insulin secretion in normal and diseased states.

[Hyperinsulinemia in vertigo, tinnitus and hearing loss]

48 patients (25 woman, mean age 42 +/- 9.9 years and 23 men, mean age 46.6 +/- 8.3 years) suffering from vertigo, tinnitus and hearing loss of unknown origin were included into this study. The occurrence and coexistence of symptoms was measured. Insulin levels were measured fasting and at the second hour of OGTT. Results were compared with the control group of 31 healthy persons (16 women, mean age 41.3 +/- 5.6 years and 15 men, mean age 47.6 +/- 9.4 years). The character of vertigo, localization of hearing loss and electronystagmographic findings showed the pathology of the inner ear. The occurrence of hyperinsulinemia was significantly more common in the patients group--43.8%, comparing to the control group--22.6%. Also the insulin levels in the second hour of OGTT, were statistically significantly higher in patients that in the control group.

Association of acanthosis nigricans with hyperinsulinemia compared with other selected risk factors for type 2 diabetes in Cherokee Indians: the Cherokee Diabetes Study

OBJECTIVE

To report prevalence rates of acanthosis nigricans (AN) and hyperinsulinemia and the association of AN with hyperinsulinemia compared with other known or suspected risk factors for type 2 diabetes in young American Indians.

RESEARCH DESIGN AND METHODS

A random sample of Cherokee Nation members aged 5-40 years was invited to participate in the Cherokee Diabetes Study, a cross-sectional study of type 2 diabetes and its risk factors in a young American Indian population. Data were collected by personal interview, medical history, physical examination (including anthropometric and blood pressure measurements and examination of the neck for AN), and laboratory analyses of blood specimens. Levels of insulin, lipids, and glucose were measured on fasting blood specimens. Diabetes status was determined according to the American Diabetes Association criteria.

RESULTS

A total of 2,205 participants were examined. Overall prevalence rates for AN and hyperinsulinemia were 34.2 and 47.2%, respectively. In general, the rates for both increased with age and degree of Indian heritage and were higher in female subjects, overweight/obese individuals, those with type 2 diabetes, and those with a parental history of type 2 diabetes. In addition, both had significantly higher age- and sex-adjusted means for selected known or suspected risk factors for type 2 diabetes. AN remained significantly associated with hyperinsulinemia (P = 0.0001) in multivariate analysis.

CONCLUSIONS

AN is independently associated with hyperinsulinemia and therefore may be useful as an early indicator of high risk for diabetes.

Association of neck circumference with insulin resistance-related factors

AIM

Overall and central obesity are associated with disorders in lipid and glucose metabolism, insulin resistance, hypertension, atherosclerosis and type 2 diabetes. Waist circumference and abdominal sagittal diameter have been suggested as the best simple anthropometric indexes of abdominal visceral fat accumulation. The aim of the present study was to test the association of neck circumference with abdominal and general obesity as well as with insulin resistance related factors.

METHOD

Neck circumference was measured in addition to the traditional anthropometric measures and blood lipids, insulin and glucose concentrations and blood pressure.

RESULTS

The prevalence rates of disorders in lipid or glucose metabolism and high fasting insulin concentrations were highest in the highest quintiles of all the anthropometric measures.

CONCLUSION

We conclude that neck circumference is associated with the metabolic disorders related to insulin resistance. The measurement of neck circumference could be useful in clinical screening for persons at an enhanced risk for insulin resistance.

Metabolic correlates with obstructive sleep apnea in obese subjects

OBJECTIVE

To examine links between obstructive sleep apnea (OSA), insulin resistance, and dyslipidemia.

STUDY DESIGN

Obese (body mass index [BMI] >95th percentile for age and gender) children who snored (n = 62, 46 males, age 10.89 [5-16 years] underwent polysomnography and metabolic studies.

RESULTS

Respiratory disturbance index (RDI) was 9.23 (0-95), with 23 children (39%) recommended for treatment. Fasting insulin levels were 154.6 pmol/L +/- 79.8 (52-486), and fasting glucose levels were high in 7 children (11%). Fasting insulin levels correlated with sleep variables, including log transformed RDI (log(10)RDI) (P =.01), desaturation events (P =.05), arousal index (P =.01), and sleep-time with oxygen saturation in arterial blood <90% (P =.03) (adjusted r (2) = 0.21, F = 3.9, P =.005), but not with age, or BMI Z score. Log(10)RDI correlated with fasting insulin (P =.001) and BMI Z score (P =.03) (adjusted r (2) = 0.12, F = 3.9, P =.005), but not age or other metabolic variables. The correlation between log(10)RDI and fasting insulin persisted in models combining sleep and metabolic variables: log(10)RDI, adjusted r (2) = 0.75, F = 35.2, P <.001, and for fasting insulin, adjusted r (2) = 0.42, F = 6.1, and P <.001.

CONCLUSIONS

The severity of OSA (log(10)RDI) correlated with fasting insulin levels, independent of BMI. Insulin levels may be further elevated as a consequence of OSA in obese children.

Clustering of silent cardiovascular risk factors in apparently healthy Hispanics

Ischaemic heart disease is one of the leading causes of cardiovascular morbidity and mortality. Because most factors leading to cardiovascular disease have a silent course, early screening is needed for prevention and for halting disease progression. In our centre, a programme was implemented in apparently healthy subjects for the early diagnosis and treatment of factors known to increment the risk of developing cardiovascular and metabolic disease. We present data from the first 153 individuals evaluated. The incidence of modifiable risk factors in our healthy population was as follows: overweight 33% (BMI: 25-30 kg/m(2)), obesity 45% (BMI >30 kg/m(2)), sedentarism 84%, arterial hypertension 15% (>140/90 mm Hg), hyperinsulinaemia 50%, glucose intolerance 14% (>160 mg/dl 120 min after 75 g glucose load), type 2 diabetes mellitus 5%, hypercholesterolaemia 50%, hypertriglyceridaemia 28%, and salt sensitivity 25%. Clustering of three or more cardiovascular risk factors was observed in 59% of the apparently healthy subjects. Obesity was associated with greater clustering of risk factors. The cardiovascular dysmetabolic syndrome was present in 72% of the obese individuals. These findings revealed a very high prevalence of cardiovascular risk factors in apparently healthy Hispanics. Even though these individuals were clinically asymptomatic, they are at increased risk for developing cardiovascular disease and type 2 diabetes mellitus. Mechanisms for the early detection and correction of modifiable risk factors in the healthy population must be implemented. Only through prevention will a reduction in the incidence of cardiovascular atherosclerotic disease and of type 2 diabetes mellitus be achieved.

Expression of type III hyperlipoproteinemia in apolipoprotein E2 (Arg158 --> Cys) homozygotes is associated with hyperinsulinemia

Type III hyperlipoproteinemia (HLP) is mainly found in homozygous carriers of apolipoprotein E2 (apoE2, Arg158-->Cys). Only a small percentage (< 5%) of these apoE2 homozygotes develops hyperlipidemia, indicating that additional environmental and genetic factors contribute to the expression of type III HLP. In the present study, first, the prevalence of type III HLP among apoE2 homozygotes was estimated in a Dutch population sample of 8888 participants. Second, 68 normocholesterolemic and 162 hypercholesterolemic apoE2 homozygotes (type III HLP patients) were collected to investigate additional factors influencing type III HLP expression. In the Dutch population sample, apoE2 homozygosity occurred with a frequency of 0.6% (57 of 8888 individuals). Among the 57 E2/2 subjects, 10 type III HLP patients were identified (prevalence 18%). Comparison of normocholesterolemic E2/2 subjects and type III HLP patients showed that the latter had a significantly increased body mass index (25.6 +/- 4.0 versus 26.9 +/- 3.8 kg/m(2), respectively; P=0.03) and prevalence of hyperinsulinemia (26% versus 63%, respectively; P<0.001). Multiple linear regression analysis demonstrated that most of the variability in type III HLP expression can be explained by fasting insulin levels (partial correlation coefficient approximately 0.50, P<0.001). In contrast to men, apoE2 homozygous women aged > or = 50 years had significantly higher plasma lipid levels than their counterparts aged < 50 years. These data demonstrate that the expression of type III HLP in E2/2 subjects is elicited to a large extent by hyperinsulinemia. In addition, in female apoE2 homozygotes, the expression increases with age; this increase is most likely due to the loss of estrogen production.

[Glucose/insulin response to a glucose overload in subjects at risk for type 2 diabetes]

With the purpose of determining how certain risk factors for type 2 diabetes such as family history of diabetes, obesity and dyslipidemia, affect the glucose-insulin response to a glucose challenge, 135 individuals (77 women and 58) men were studied. Their ages ranged from 20-68 years, their basal glycemic values were less than 110 mg/dL but they were considered at risk for diabetes due to the presence of one or more of those factors. We found that the presence of those risk factors did not affect the glycemic response in any case. However, the basal insulin levels as well as the post-challenge values were increased significantly (p < 0.0001) by the presence of obesity in men as well as in women. Dyslipidemia increased the basal and post challenge glucose insulin values only in men (p < 0.002). The coexistence of obesity and family history of diabetes provoked a decrease in the basal insulin levels as well as in the insulin response to glucose. We conclude that, without alteration of the glycemic response, the presence of risk factors as obesity, dyslipidemia or family history of diabetes leads to basal hyperinsulinemia, as well as glucose stimulated hyperinsulinemia, however the coexistence of obesity and family history of diabetes, is responsible for a deficit in the insulin secretion by the pancreas.

Proteinuria and cardiovascular disease

In the last few decades, clinical and experimental data have established microalbuminuria/proteinuria as an independent risk factor for renal disease and for progression of renal disease in patients with diabetes and in those with essential hypertension. Reduction of proteinuria with the use of angiotensin-converting enzyme inhibitors has been shown in clinical trials to delay or stabilize the rate of progression of renal disease. This effect appears to be independent of any effect on blood pressure control. In conjunction with other therapeutic interventions such as dietary modification and control of serum lipids, it appears that for at least a subgroup of patients, it is possible to delay or prevent progression of kidney failure. More recently, evidence has accumulated that establishes microalbuminuria/proteinuria as an independent risk factor for cardiovascular morbidity and mortality even in those without other clinical evidence of kidney disease. There is frequently a clustering of risk factors in these individuals that includes insulin resistance, salt-sensitivity, hypertension, and dyslipidemia. The mechanism of this relationship of proteinuria and cardiovascular disease is unclear, but the presence of proteinuria as a marker for cardiovascular disease has important implications for the identification and treatment of individuals at risk.

[Biological, familial and metabolic characteristics of infantile and juvenile obesity]

BACKGROUND

Obesity is the most prevalent nutritional disease in people of less than 20 years old.

AIM

To report biological, familial and metabolic characteristics in obese children.

PATIENTS AND METHODS

A retrospective review of 187 children seen at obesity clinics and that had a complete metabolic study.

RESULTS

Ninety five prepuberal and 92 puberal children, aged 8.7 +/- 2.2 and 12.6 +/- 2.2 years old respectively, were studied. Body mass index was over 4 standard deviations in 48.4% of prepuberal children and in 39.1% of puberal children. Paternal obesity was twice more prevalent (30.2%) than in the general population. The daily caloric intake and basal metabolic rate (BMR) were within the normal range; nevertheless there was a positive caloric balance due to minimal physical activity. The mean daily fat intake was normal (26.4 +/- 8.5 and 25.3 +/- 9.1% of total calories in prepuberal and puberal children respectively). The daily fiber intake was under 70% of recommendation. The total cholesterol was over 200 mg/dl in 26.6 and 23.9% of prepuberal and puberal children. LDL cholesterol was over 130 mg/dl in 27.3 and 26.6% and triacylglycerol was over 150 mg/dl in 16.9 and 25% of prepuberal and puberal children respectively. Basal serum insulin was over 20 uIU/ml in 27.7 and 42.2% of prepuberal and puberal children, respectively. Post glucose serum insulin was over 60 uIU/ml in 40 and 63% of prepuberal and puberal children, respectively.

CONCLUSIONS

Infantile and juvenile obesity is a chronic disease with a high incidence of metabolic alterations.

Sample exchange to compare insulin measurements between the San Antonio Heart Study and the Framingham Offspring Study

Lack of assay standardization has precluded cross-study comparison of insulin levels. We exchanged blood samples between the San Antonio Heart and Framingham Offspring Studies to compare insulin measurements. Two randomly selected specimens were chosen for each non-diabetic man and woman in each of the bottom four quintiles and top two deciles of the originally assayed fasting and 2-hour post-challenge insulin distributions: 48 plasma samples from Framingham, and after further stratification by ethnicity, 96 serum samples from San Antonio. Total immunoreactive insulin was originally measured in both studies; we repeated the identical assay on exchanged samples. Repeat assays were performed a mean (SD) of 7.0 (0.8) years after collection in the Framingham study and 4.6 (1.1) years in the San Antonio study. Repeat insulin levels were highly correlated with original levels for both San Antonio samples repeated in Framingham (Pearson r=0.923) and for Framingham samples repeated in San Antonio (r=0.959). Original and repeat San Antonio serum insulin levels were similar (mean fasting and 2-hour combined original level 154 pmol/l vs. 142 pmol/l on repeat in Framingham). Framingham plasma insulin levels repeated in San Antonio were substantially lower than original levels (120 pmol/l vs. 336 pmol/l), as were an additional 12 samples repeat assayed in Framingham (93 pmol/l vs. 320 pmol/l). Repeat rank ordering in both studies was excellent: over 90% of subjects originally classified as hyperinsulinemic (top tertile of the combined distribution) were again classified as hyperinsulinemic upon repeat assay. We conclude that sample exchange for insulin measurement is simple and feasible. Original and repeat insulin levels are highly correlated; subjects originally classified as hyperinsulinemic remain so classified upon repeat assay. Associated regression curves can be used to calibrate insulin levels to a common reference standard, allowing epidemiology studies to compare levels of insulin and associated risk factors.

Hyperinsulinemia for the development of hypertension: data from the Hawaii-Los Angeles-Hiroshima Study

The present study was to assess the association of metabolic factors including hyperinsulinemia, with the development of hypertension in Japanese-Americans. One hundred forty normotensive (<140/90 mmHg) subjects aged 40 to 69 years old from the Hawaii-Los Angeles-Hiroshima study were followed for 15 years. Patients with cardiovascular disease were excluded. Body mass index (BMI), blood pressure (BP), serum total cholesterol (TC), triglycerides (TG), uric acid (UA), and glucose and insulin responses at baseline, 1 h, and 2 h after a glucose load were analyzed. Seventeen subjects became hypertensive (systolic BP > or = 160 mmHg, diastolic BP > or = 95 mmHg, or received drug treatment) during follow-up. Age- and sex-adjusted BMI, BP, serum UA, TG, insulin, and changes in fasting glucose during follow-up were higher in subjects who later became hypertensive than in those who did not. There was no difference in the change in BMI. Age- and sex-adjusted relative risks for the development of hypertension by quartiles of BMI, serum UA, TG, and the sum of insulin values (sigmainsulin) during a glucose load were highest in highest quartile of the distribution. When age, sex, systolic BP, BMI, serum UA, TC, TG, fasting glucose, sigmainsulin, and the change in BMI were used in a proportional hazard analysis, hyperinsulinemia, hyperuricemia, and systolic BP were found to be significant risk factors for hypertension. In conclusion, hyperinsulinemia, as well as obesity, hyperuricemia, and hypertriglyceridemia were associated with hypertension in Japanese-Americans. Hyperinsulinemia and hyperuricemia were independent predictors of the development of hypertension.

Hormone profiles in young adults with epilepsy treated with sodium valproate or lamotrigine monotherapy

PURPOSE

Treatment with sodium valproate (VPA) may be associated with polycystic ovarian syndrome (PCOS) in some women with epilepsy. By comparing hormone profiles in young adults taking VPA or lamotrigine (LTG) as monotherapy, this study aimed to explore whether a pharmacologic effect of VPA could be responsible for this observation.

METHODS

Hormone profiles in men and women taking VPA (n = 40) or LTG (n = 36) monotherapy for epilepsy were compared. None of the women were receiving hormonal contraception or replacement. Patients gave details of seizure type and frequency, menstrual cycle, and medical and drug history. Body mass index was calculated, and fasting insulin, glucose, cholesterol, triglycerides (TG), high- and low-density lipoproteins, testosterone, dihydroepiandosterone (DHEA), androstenedione, sex hormone-binding globulin (SHBG), free androgen index (FAI), luteinising hormone (LH), follicle-stimulating hormone (FSH), and antiepileptic drug (AED) concentrations were measured.

RESULTS

There were no differences between treatment groups for both sexes in age and seizure control. Only four obese VPA-treated women were hyperinsulinaemic (p = 0.05); three with abnormal menstrual cycles; one with raised testosterone. Testosterone (p = 0.02), FAI (p = 0.03), and TG (p = 0.02) levels were higher, however, in women taking the drug. Obese patients of both sexes (p = 0.01) and VPA-treated men (p = 0.03) had higher insulin concentrations.

CONCLUSIONS

VPA therapy may be associated with subclinical elevation in fasting insulin levels. Testosterone and TG levels were higher in VPA-treated women compared with the levels in those taking LTG. However, only a minority of obese females exhibited biochemical characteristics suggestive of PCOS. Biochemical screening may allow women at risk of developing PCOS to avoid VPA.

Lipolysis in African-American children: is it a metabolic risk factor predisposing to obesity?

Rates of obesity and type 2 diabetes are higher in African-American (AA), compared with American white (AW), adults and children. It is not known whether biologic and/or environmental differences are responsible for this racial disparity. We and others have demonstrated that AA children are hyperinsulinemic, compared with their AW peers. This investigation tested the hypothesis that hyperinsulinemia in AA children is associated with lower rates of lipolysis, which could be a risk factor for future obesity. Forty prepubertal children (20 AA and 20 AW) with comparable body composition (assessed by dual-energy x-ray absorptiometry) and visceral adiposity (evaluated with computed tomography scan) were studied. Total body lipolysis was measured with [(2)H(5)]glycerol after overnight fasting. Basal lipolysis was approximately 40% lower in AA vs. AW children, whether the data were expressed for total body (85.7 +/- 8.9 vs. 130.3 +/- 14.1 micromol/min, P = 0.011) or per-kilogram BW (2.4 +/- 0.2 vs. 3.8 +/- 0.4 micromol/min.kg, P = 0.002) or per kilogram fat free mass (FFM) (3.3 +/- 0.3 vs. 5.2 +/- 0.5 micromol/min.kg FFM, P = 0.004), or per kg fat mass (FM) (13.7 +/- 1.6 vs. 21.3 +/- 3.3 micromol/min.kg FM, P = 0.046). Fasting insulin levels were higher in AA children (99.6 +/- 7.8 vs. 77.4 +/- 5.9 pmol/L, P = 0.032). Lipolysis correlated positively with fat mass, percent body fat, and abdominal fat mass. However, in multiple-regression analysis models after controlling for insulin and body composition, race remained a significant contributor to the variance in lipolysis. In summary, the present study demonstrates that rates of lipolysis are significantly lower in AA children, compared with their white peers. This may constitute an early metabolic phenotype that may mediate fat trapping and susceptibility to obesity in a specific environmental context of energy excess conducive to fat accretion.

Clustering of cardiovascular risk factors with diabetes in Chinese patients: the effects of sex and hyperinsulinaemia

OBJECTIVE

This study was designed to investigate factors which affect the clustering of cardiovascular risk factors with diabetes in Chinese patients.

RESEARCH DESIGN AND METHODS

Six hundred and fifty-four patients with diabetes were assessed comprehensively for diabetes complications and cardiovascular risk factors in a metropolitan hospital in Beijing, China. Insulin resistance and secretion were also evaluated by measurement of glucose and insulin levels before and after a meal tolerance test. Results were analysed according to patient groups stratified by the number of cardiovascular risk factors coexisting with diabetes.

RESULTS

Cardiovascular risk factors were common in Chinese diabetic patients. The clustering of three or more of these factors with diabetes occurred more often than by chance alone and was associated with postprandial hyperinsulinaemia. Patients with a high number of risk factors were more prone to macrovascular events but did not have higher albuminuria. Using the commonly adopted lower threshold for diagnosing obesity and central obesity in women, there were more women with multiple risk factors. However, this disappeared if the same criteria were used for men and women. Even in the presence of diabetes, cardiovascular risk factors were inadequately controlled in most patients.

CONCLUSIONS

The concurrence of diabetes and other cardiovascular risk factors which constitute the metabolic syndrome is a common phenomenon in urban Chinese diabetic patients. It is associated with hyperinsulinaemia and possibly the female sex. This study emphasises the importance of public health measures to control cardiovascular risk factors in patients with diabetes.

Prevalence of acanthosis nigricans and its association with hyperinsulinemia in New Mexico adolescents

PURPOSE

To determine whether the association between acanthosis nigricans (AN) and hyperinsulinemia is independent of obesity and other variables.

METHODS

A convenience sample of 675 New Mexico middle school students was screened to determine the presence of AN, obesity, and other variables, including: ethnicity, parental history of diabetes, and level of physical activity. Fasting glucose and insulin levels were drawn on 233 students to determine the association between risk factors and hyperinsulinemia.

RESULTS

Acanthosis nigricans (AN) was present in 18.9% of students screened. Twenty-one percent of the subsample had hyperinsulinemia. Based on these results, the estimated prevalence of hyperinsulinemia among all middle school students in New Mexico was 8.9%. Forty-seven percent (47.2%) of students who had AN and were obese had hyperinsulinemia, compared with 2.4% of students who did not have either of these conditions. In multiple logistic regression analysis, AN and obesity were independently and positively associated with hyperinsulinemia, whereas physical activity was protective.

CONCLUSIONS

The high prevalence of risk factors in this population makes diabetes prevention a priority for public health action. AN screening is an easily performed, noninvasive method for identifying adolescents at risk for type 2 diabetes.

Hyperinsulinemia predicts fatal liver cancer but is inversely associated with fatal cancer at some other sites: the Paris Prospective Study

OBJECTIVE

To investigate whether insulin is a risk factor for death by site-specific cancers.

RESEARCH DESIGN AND METHODS

This was a prospective cohort study of 6,237 nondiabetic French working men between ages 44 and 55 years at baseline from the Paris Prospective Study cohort. Death by site-specific cancers was investigated in relation to baseline insulin concentrations during fasting and 2 h after a 75-g oral glucose tolerance test.

RESULTS

Of the original 6,237 men in the cohort, 1.739 died over the 23.8 years of follow-up. 778 (45%) from cancer. Baseline hyperinsulinemia, both fasting and 2-h, was significantly associated with fatal liver cancer, with age-adjusted standardized hazards ratios of 2.72 (95% CI 1.87-3.94) and 3.41 (2.23-5.21). In contrast, fasting hyperinsulinemia was inversely associated with fatal lip, oral cavity, and pharynx cancer and larynx cancer, with hazards ratios of 0.55 (0.41-0.75) and 0.63 (0.47-0.83), respectively; 2-h insulin concentrations were inversely associated with stomach and larynx cancers (hazards ratios 0.62 [0.43-0.90] and 0.66 [0.50-0.891, rcspectively). These relationships were stable after adjusting for other risk factors. Insulin concentrations remained negatively associated with deaths from these cancers in analyses restricted to men who smoked and in those who were not chronic alcohol consumers.

Genetic versus environmental aetiology of the metabolic syndrome among male and female twins

AIMS/HYPOTHESIS

The aetiology of the metabolic syndrome including hyperinsulinaemia, glucose intolerance, dyslipidaemia, hypertension and obesity is not known. We studied the relative impact of genetic versus environmental factors for the development of the components in the syndrome among male and female twins.

METHODS

A total of 303 elderly twin pairs participated in the study. We report concordances and heritability estimates of the components by classic twin analysis to assess the proportion of variation attributed to genetic factors.

RESULTS

All components correlated significantly. The concordance rates for glucose intolerance, overall obesity and low HDL-cholesterol were significantly higher among monozygotic than dizygotic twins indicating a genetic influence on the development of these phenotypes. The heritability estimates for glucose concentration, BMI and HDL-cholesterol among monozygotic twins confirmed these findings. The heritability estimates for waist-to-hip ratio, fasting insulin and triglycerides, however, were low, indicating a major environmental influence. We found a higher genetic influence on glucose intolerance and systolic blood pressure and a lower genetic influence on low HDL-cholesterol and diastolic blood pressure among male twins compared to female twins.

CONCLUSION/INTERPRETATION

Based on the correlations between the components in the syndrome, we propose a core complex including hyperinsulinaemia, obesity, hypertriglyceridaemia and low HDL-cholesterol with only weak associations to glucose concentrations and blood pressure levels. The study confirms the notion of a multifactorial aetiology of the components including genetic and non-genetic factors. The differences in aetiology between male and female twins indicate an influence of sex on several of the components in the metabolic syndrome.

Insulin resistance and elevated levels of tissue plasminogen activator in first-degree relatives of South Asian patients with ischemic cerebrovascular disease

BACKGROUND AND PURPOSE

South Asians in the United Kingdom suffer from an increased mortality from cerebrovascular disease compared with whites. Evidence suggests that the relatives of white stroke patients are at increased risk of vascular disease. The aim of this study was to investigate atherothrombotic risk factors in the first-degree relatives of South Asian patients suffering from ischemic cerebrovascular disease and to compare them with South Asian subjects free from clinically detectable cerebrovascular disease.

METHODS

We compared 143 relatives of South Asians with ischemic stroke (South Asian relatives group) with 146 South Asian control subjects from West Yorkshire, UK.

RESULTS

The ages and ethnic and sex distributions of South Asian relatives and South Asian controls were similar. There were no significant differences in body mass index, waist-hip ratio, number of current smokers, and past medical history of hypertension, diabetes mellitus, or myocardial infarction between the 2 groups. Fasting blood glucose, glycosylated hemoglobin (HbA(1c)), total cholesterol, triglycerides, and HDL cholesterol were similar in the 2 groups. Fasting insulin (South Asian relatives, 12.0; South Asian controls, 8.5 mU/L; P<0.0001) (independent of tissue plasminogen activator) and insulin resistance (derived by Homeostasis Model Assessment) (South Asian relatives, 2.7; South Asian controls, 1.9; P=0.001) were significantly raised in stroke relatives. Stroke relatives showed elevated levels of tissue plasminogen activator (South Asian relatives, 11.6; South Asian controls, 8.4 ng/mL; P<0.0001), which was independent of plasma insulin. There were no differences in plasminogen activator inhibitor antigen or activity between the groups.

CONCLUSIONS

South Asians stroke relatives exhibit hyperinsulinemia, increased insulin resistance, and increased tissue plasminogen activator levels. These observations might account for increased susceptibility to atherothrombotic disease in this ethnic group.

Evaluation of growth and hormonal status in patients referred to the International Fanconi Anemia Registry

OBJECTIVES

1) To determine the extent of short stature in patients with Fanconi anemia (FA); 2) to determine the extent and nature of endocrinopathy in FA; 3) to assess the impact on height of any endocrinopathies in these patients; and 4) to study the correlation, if any, between height, endocrinopathy, and FA complementation group.

STUDY DESIGN

Fifty-four patients with FA, 30 males and 24 females from 47 unrelated families, were prospectively evaluated in a Pediatric Clinical Research Center. The patients ranged in age from 0.1-31.9 years, with the mean age at assessment 8.6 years.

RESULTS

Endocrine abnormalities were found in 44 of the 54 FA patients tested (81%), including short stature, growth hormone (GH) insufficiency, hypothyroidism, glucose intolerance, hyperinsulinism, and/or overt diabetes mellitus. Twenty-one of 48 (44%) participants had a subnormal response to GH stimulation; 19 of 53 (36%) had overt or compensated hypothyroidism, while 8 of 40 participants had reduced thyroid-hormone binding. Two patients were diabetic at the time of study; impaired glucose tolerance was found in 8 of 40 patients (25%), but most surprisingly, hyperinsulinemia was present in 28 of 39 (72%) participants tested. Significantly, spontaneous overnight GH secretion was abnormal in all patients tested (n = 13). In addition, participants demonstrated a tendency toward primary hypothyroidism with serum tetraiodothyronine levels at the lower range of normal, while also having thyrotropin (thyroid-stimulating hormone) levels at the high end of normal. Sixteen patients were assigned to FA complementation group A, (FA-A), 12 to FA-C, and 5 to FA-G; 10 of the 12 participants in FA-C were homozygous for a mutation in the intron-4 donor splice site of the FANCC gene. Patients in groups FA-A and FA-G were relatively taller than the group as a whole (but still below the mean for the general population), whereas those in FA-C had a significantly reduced height for age. GH response to stimulation testing was most consistently normal in participants from FA-G, but this did not reach statistical significance. The tendency toward hypothyroidism was more pronounced in participants belonging to complementation groups FA-C and FA-G, whereas insulin resistance was most evident in patients in FA-G, and least evident in those in FA-C. Short stature was a very common finding among the patients with a mean height >2 standard deviations below the reference mean (standard deviation score: -2.35 +/- 0.28). Patients with subnormal GH response and those with overt or compensated hypothyroidism were shorter than the group with no endocrinopathies. The heights of those participants with glucose or insulin abnormalities were less severely affected than those of normoglycemic, normoinsulinemic participants, although all were significantly below the normal mean. The mean height standard deviation score of patients with entirely normal endocrine function was also >2 standard deviations below the normal mean, demonstrating that short stature is an inherent feature of FA.

CONCLUSION

Endocrinopathies are a common feature of FA, primarily manifesting as glucose/insulin abnormalities, GH insufficiency, and hypothyroidism. Although short stature is a well-recognized feature of FA, 23 patients (43%) were within 2 standard deviations, and 5 of these (9% of the total) were actually above the mean for height for the general population. Those patients with endocrine dysfunction are more likely to have short stature. These data indicate that short stature is an integral feature of FA, but that superimposed endocrinopathies further impact on growth. The demonstration of abnormal endogenous GH secretion may demonstrate an underlying hypothalamic-pituitary dysfunction that results in poor growth.

Intra-urban differences in the prevalence of the metabolic syndrome in southern India -- the Chennai Urban Population Study (CUPS No. 4)

AIMS

To assess the influence of socioeconomic status on the prevalence of the metabolic syndrome in an urban south Indian population in Chennai.

METHODS

The Chennai Urban Population Study is an epidemiological study involving two residential colonies in Chennai (formerly Madras) in south India representing the middle and lower income groups. All individuals > or = 20 years of age living in the colonies were invited to participate in the study. Of the total 1399 eligible subjects, 1262 individuals (479 belonging the middle income group colony and 783 from the low income group colony) participated in the study. The overall response rate was 90.2%. The main outcome measures were the prevalence rates of the various components of the metabolic syndrome.

RESULTS

There were significant differences in the socioeconomic status and lifestyle of the inhabitants of the two areas. The mean monthly income of the Tirumangalam (middle income) group (Rs8075 +/- 3859) was significantly higher than the T. Nagar (low income) group (Rs1399 +/- 916). The dietary profile of the middle income group showed higher intake of calories, fat and sugar compared to low income group (P < 0.001). The age-standardized prevalence rates of the various components of the metabolic syndrome were significantly higher in the middle compared to the low income group - diabetes (12.4 vs. 6.5%), impaired glucose tolerance (7.5 vs. 2.9%), hypertension (14.9 vs. 8.4%), obesity (males 38 vs. 13.4%, females 33.1 vs. 24.2%), hypercholesterolaemia (24.2 vs. 14.2%) and hyperinsulinaemia (16.7 vs. 6.6%) P < 0.001). Although the prevalence of coronary artery disease and hypertriglyceridaemia were higher in the middle income group, the differences did not reach statistical significance. The relative odds ratio for diabetes and impaired glucose tolerance increased significantly with increase in income while hypercholesterolaemia, hypertriglyceridaemia, hypertension and coronary artery disease showed no significant changes. Logistic regression analysis revealed that geographical area (higher social class) had a strong association with the components of the metabolic syndrome even after inclusion of other risk factors like age and body mass index in the model.

CONCLUSIONS

Significant differences exist in the prevalence of various components of the metabolic syndrome even within an urban environment and this appears to be influenced by socioeconomic status.

The effects of metformin on body mass index and glucose tolerance in obese adolescents with fasting hyperinsulinemia and a family history of type 2 diabetes

OBJECTIVES

The prevalence of type 2 diabetes in American adolescents has increased markedly during the past generation. Although the factors that contribute to the development of type 2 diabetes are complex and not wholly elucidated, the triad of severe obesity, hyperinsulinemia, and a family history of type 2 diabetes places a child at an increased risk for development of the disease. Current approaches to the prevention of type 2 diabetes, including dietary counseling and exercise, have had limited success. We reasoned that drugs that increase glucose tolerance in diabetic patients might prove useful in preventing the progression to glucose intolerance in high-risk patients. To that end, we conducted a double-blind, placebo-controlled study of the effects of metformin on body mass index (BMI), serum leptin, glucose tolerance, and serum lipids in obese adolescents with fasting hyperinsulinemia and a family history of type 2 diabetes.

METHODS

The study population consisted of 29 white and black adolescents aged 12 to 19 years. All had BMIs exceeding 30 kg/m(2). Criteria for enrollment included: 1) a fasting insulin concentration exceeding 15 microU/mL; and 2) at least 1 first- or second-degree relative with type 2 diabetes. All patients had fasting plasma glucose concentrations <110 mg% and hemoglobin A1c concentrations </=6.0%. All had normal linear growth and sexual development for age, with no marked hirsutism, severe acne, or menstrual irregularities characteristic of polycystic ovary syndrome. Eight participants had acanthosis nigricans. After baseline laboratory studies including a rapidly sampled intravenous glucose tolerance test, patients were randomized to receive metformin (500 mg twice daily) or a placebo for a total of 6 months. The effects of metformin on BMI standard deviation score, serum leptin, glucose tolerance, and serum lipids were analyzed. The study was double-blinded and included no specific dietary restrictions.

RESULTS

Metformin caused a decline of 0.12 standard deviation in BMI in study participants (-1.3% from baseline), and a 5.5% reduction in serum leptin in girls. In contrast, BMI and serum leptin rose 0.23 standard deviation (2.3%) and 16.2%, respectively, in the placebo group during the treatment period. Metformin caused a progressive decline in fasting blood glucose (from a mean of 84.9 to 75.1 mg%) and a reduction in fasting insulin levels (from 31.3 to 19.3 microU/mL). In contrast, fasting glucose levels in the placebo group rose slightly from 77.2 to 82.3 mg%, and fasting insulin levels did not change. Insulin sensitivity, as assessed by the ratio of fasting insulin to glucose concentrations and the quantitative insulin sensitivity check index (1/[log fasting insulin + log fasting glucose]) and homeostasis model assessment insulin resistance index (fasting insulin x fasting glucose/22.5) indices, increased slightly in the metformin-treated participants. However, the insulin sensitivity measured using Bergman's minimal model did not change. There were also no significant changes in glucose effectiveness, hemoglobin A1c, serum lipids, or serum lactate in the metformin or placebo groups. Metformin was tolerated well by the majority of patients. Transient abdominal discomfort or diarrhea occurred in 40% of treated participants; there were no episodes of vomiting or lactic acidosis.

CONCLUSIONS

The treatment of obesity and insulin resistance in adults often proves ineffective because the vicious cycle leading to type 2 diabetes may have become entrenched and, to some extent, may be irreversible. Early detection and therapy of the obese adolescent with a family history of type 2 diabetes may interrupt the cycle of weight gain and insulin resistance that leads to glucose intolerance in adulthood. Through its ability to reduce fasting blood glucose and insulin concentrations and to moderate weight gain, metformin might complement the effects of dietary and exercise counseling and reduce the risk of type 2 diabetes in selected patients.

On the association between valproate and polycystic ovary syndrome

Recent studies by Isojärvi et al. have raised the issue of an increased incidence of polycystic ovary syndrome (PCOS) in women with epilepsy treated with valproate (VPA) and have proposed replacement with lamotrigine (LTG). Polycystic ovaries (PCO) are a common finding, with a prevalence >20% in the general population, and are easily detected by pelvic or vaginal ultrasonography, whereas PCOS is comparatively rare: few women with PCO have fully developed PCOS, which includes hirsutism, acne, obesity, hypofertility. hyperandrogenemia, and menstrual disorders. From an extensive review of the current literature, it appears that there are no reliable data on the actual prevalence of PCOS in normal women and in women with epilepsy. The pathogenesis of PCO is multifactorial, including genetic predisposition and the intervention of environmental factors, among which weight gain and hyperinsulinism with insulin resistance may play a part. The roles of central (hypothalamic/pituitary), peripheral, and local ovarian factors are still debated. PCO and PCOS appear to be more frequent in women with epilepsy, but there are no reliable data showing a greater prevalence after VPA. The recent studies by Isojärvi et al. may have been biased by the retrospective selection of patients. To date, there is no reason to contraindicate the use of VPA in women with epilepsy. However, patients should be informed about the risk of weight gain and its consequences.

Hyperinsulinemia and hemostatic abnormalities are associated with silent lacunar cerebral infarcts in elderly hypertensive subjects

OBJECTIVES

We sought to study the association of the silent cerebral infarct (SCI), a predisposing condition of stroke, with hyperinsulinemia and hemostatic abnormalities in older hypertensive subjects.

BACKGROUND

Hypertension is a powerful risk factor for stroke. However, the role of other risk factors for stroke in hypertensive subjects remains incompletely understood.

METHODS

We performed brain magnetic resonance imaging and measured cardiovascular risk factors, by administering the 75-g oral glucose tolerance test and measuring plasma insulin and hemostatic variables, in 123 asymptomatic hypertensive subjects (mean age 69 years).

RESULTS

At least one SCI was detected in 80 subjects (65%), and multiple SCIs were found in 48 subjects (39%). The presence of SCIs was associated with older age, higher levels of 24-h systolic blood pressure, 2-h insulin, thrombin-generation markers (prothrombin fragment 1+2 and thrombin-antithrombin complexes), plasminogen activator inhibitor-1 (PAI-1), D-dimer and von Willebrand factor (vWF), but not with plasmin-alpha2-plasmin complex (PIC) levels. The 2-h insulin area under the curve (AUC) was positively correlated with PAI-1 and vWF levels (p < 0.01), and the PAI-1 level was negatively correlated with the PIC level (p < 0.02). Multiple logistic regression analysis revealed that age and the 2-h insulin AUC were significantly associated with SCIs, particularly those located in the subcortical white matter, and hemostatic abnormalities were significantly associated with the presence of multiple SCIs, particularly those located in the basal ganglia.

CONCLUSIONS

In older asymptomatic hypertensive subjects, hyperinsulinemia appears to be associated with lacunar-type SCIs, particularly those located in the subcortical white matter, and hemostatic abnormalities show an association with the presence of multiple SCIs, particularly those located in the basal ganglia.