High blood pressure and insulin resistance: influence of ethnic background

Non-linear relationship between pulse pressure and the risk of prediabetes: a 5-year cohort study in Chinese adults

Previous research has established a strong link between pulse pressure (PP) and diabetes, but there is limited investigation into the connection between PP and prediabetes. This study aims to explore the potential association between PP and prediabetes. A retrospective cohort study encompassed 202,320 Chinese adults who underwent health check-ups between 2010 and 2016. Prediabetes was defined in accordance with the World Health Organization criteria, indicating impaired fasting glucose, with fasting blood glucose levels ranging from 6.1 to 6.9 mmol/L. To assess the PP-prediabetes relationship, we employed Cox regression analysis, sensitivity analysis, and subgroup analysis. Cox proportional hazards regression, coupled with cubic spline functions and smooth curve fitting, helped elucidate the non-linear PP-prediabetes relationship. Upon adjusting for confounding factors, we observed a positive association between PP and prediabetes (HR 1.15, 95% CI 1.11-1.18, P < 0.0001). Participants in the fourth quartile (PP ≥ 51 mmHg) had a 73% higher likelihood of developing prediabetes compared to those in the first quartile (PP < 36 mmHg) (HR 1.73, 95% CI 1.52-1.97, P < 0.0001). Moreover, the relationship between PP and prediabetes was non-linear. A two-piece Cox proportional hazards regression model identified an inflection point at 40 mmHg for PP (P for log-likelihood ratio test = 0.047). Sensitivity and subgroup analyses corroborated the robustness of our findings. Our study reveals a non-linear correlation between PP and prediabetes, signifying an increased risk of prediabetes when PP levels exceed 40 mmHg. This discovery has significant clinical implications for early prediabetes prevention and intervention, ultimately contributing to improved patient outcomes and quality of life.

Relationship between blood pressure reverse dipping and type 2 diabetes in hypertensive patients

Recent studies suggested that nocturnal variations of blood pressure (BP) were closely related to type 2 diabetes. However, little information has been revealed about the relationship between reverse-dipper pattern of BP and type 2 diabetes. In this cross-sectional study, BP variations of 531 hypertensive patients were evaluated with ambulatory BP monitoring (ABPM). Diagnosis of diabetes in Chinese adults was made according to diabetes diagnostic criteria of 2015. Multivariate logistic regression was used to examine the relationships between type 2 diabetes and ABPM results. In the study, patients with reverse-dipper pattern (32.3%) had the highest prevalence of type 2 diabetes compared with dippers (21.4%) and nondippers (23.3%). After multivariate logistic regression, reverse-dipper BP pattern (OR 2.067, P = 0.024) and nondipper BP pattern (OR 1.637, P = 0.039) were found to be correlated with type 2 diabetes compared with dipper pattern. The results of our study also suggested that type 2 diabetes might contribute to the reverse-dipper pattern of BP (OR 1.691, P = 0.023). In addition, fasting glucose was negatively correlated with the decline rate of nocturnal SBP (r = -0.095, P = 0.029). Reverse-dipper pattern of BP in ABPM may be independently associated with type 2 diabetes in patients with hypertension.

Diabetes and hypertension: the bad companions

High blood pressure is reported in over two-thirds of patients with type 2 diabetes, and its development coincides with the development of hyperglycaemia. Many pathophysiological mechanisms underlie this association. Of these mechanisms, insulin resistance in the nitric-oxide pathway; the stimulatory effect of hyperinsulinaemia on sympathetic drive, smooth muscle growth, and sodium-fluid retention; and the excitatory effect of hyperglycaemia on the renin-angiotensin-aldosterone system seem to be plausible. In patients with diabetes, hypertension confers an enhanced risk of cardiovascular disease. A blood pressure of lower than 140/85 mm Hg is a reasonable therapeutic goal in patients with type 2 diabetes according to clinical trial evidence. People with controlled diabetes have a similar cardiovascular risk to patients without diabetes but with hypertension. A renin-angiotensin system blocker combined with a thiazide-type diuretic might be the best initial antihypertensive regimen for most people with diabetes. In general, the positive effects of antihypertensive drugs on cardiovascular outcomes outweigh the negative effects of antihypertensive drugs on glucose metabolism.

Insulin resistance and risk of incident hypertension among men

J Clin Hypertens (Greenwich). 2009;11:483-490. (c) 2009 Wiley Periodicals, Inc.The independent association between insulin resistance and the development of hypertension remains in doubt because insulin resistance correlates with other metabolic factors also proposed to be associated with hypertension. The authors examined the association between the insulin sensitivity index and incident hypertension in a prospective nested case-control study among 1453 men (mean age, 61 years) who participated in the Health Professionals' Follow-up Study. The authors computed the insulin sensitivity index for each man in the study based on fasting insulin and triglyceride levels. Logistic regression was performed conditioned on age and adjusted for standard hypertension risk factors as well as renal function, cholesterol, and uric acid. The insulin sensitivity index was 6% lower in the cases compared with the controls (P<.001). The multivariable odds ratio for hypertension comparing the lowest with highest quartile of insulin sensitivity index was 1.09 (0.71-1.65) among the entire sample. However, the association between the insulin sensitivity index and incident hypertension differed significantly by age (P interaction <.001). Among men younger than 60 years, the multivariable odds ratio for the lowest compared with highest quartile was 1.93 (1.01-3.71) but was 0.67 (0.37-1.24) among older men. Insulin resistance is independently associated with incident hypertension among younger men.

Role of the IRS-1 and/or -2 in the Pathogenesis of Insulin Resistance in Dahl Salt-Sensitive (S) Rats

Insulin resistance is a common finding in hypertensive humans and animal models. The Dahl salt-sensitive (S) rat is an ideal model of genetically predetermined insulin resistance and salt-sensitive hypertension. Along the insulin signaling pathway, the insulin receptor substrates 1 and 2 (IRS-1 and -2) are important mediators of insulin signaling. IRS-1 and/or IRS-2 genetic variant(s) and/or enhanced serine phosphorylation correlate with insulin resistance. The present commentary was designed to highlight the significance of IRS-1 and/or -2 in the pathogenesis of insulin resistance. An emphasis will be given to the putative role of IRS-1 and/or -2 genetic variant(s) and serine phosphorylation in precipitating insulin resistance.

Prevalence of insulin resistance and its association with metabolic syndrome criteria among Bolivian children and adolescents with obesity

BACKGROUND

Obesity is a one of the most common nutritional disorder worldwide, clearly associated with the metabolic syndrome, condition with implications for the development of many chronic diseases. In the poorest countries of Latin America, malnourishment is still the most prevalent nutritional problem, but obesity is emerging in alarming rates over the last 10 years without a predictable association with metabolic syndrome. The objective of our study was to determine the association between insulin-resistance and components of the metabolic syndrome in a group of Bolivian obese children and adolescents. The second objective was determining the relation of acanthosis nigricans and insulin-resistance.

METHODS

We studied 61 obese children and adolescents aged between 5 and 18 years old. All children underwent an oral glucose tolerance test and fasting blood sample was also obtained to measure insulin, HDL, LDL and triglycerides serum level. The diagnosis of metabolic syndrome was defined according to National Cholesterol Education Program-Adult Treatment Panel (NCEP-ATP III) criteria adapted for children.

RESULTS

Metabolic syndrome was found in 36% of the children, with a higher rate among males (40%) than females (32.2%) (p = 0.599). The prevalence of each of the components was 8.2% in impaired glucose tolerance, 42.6% for high triglyceride level, 55.7% for low levels of high-density lipoprotein cholesterol, and 24.5% for high blood pressure. Insulin resistance (HOMA-IR > 3.5) was found in 39.4% of the children, with a higher rate in males (50%) than females (29%). A strong correlation was found between insulin resistance and high blood pressure (p = 0.0148) and high triglycerides (p = 0.002). No statistical significance was found between the presence of acanthosis nigricans and insulin resistance.

CONCLUSION

Metabolic syndrome has a prevalence of 36% in children and adolescent population in the study. Insulin resistance was very common among children with obesity with a significant association with high blood pressure and high triglycerides presence.

Improved clinical outcomes using a culturally sensitive diabetes education program in a Hispanic population

PURPOSE

The purpose of this study was to evaluate the effects of a culturally sensitive diabetes education program for Hispanics with type 2 diabetes.

METHODS

This study is a prospective cohort study to test the impact of a comprehensive diabetes education program on blood glucose control on Hispanics with type 2 diabetes. The educational program focused on maintaining glycemic control and general aspects of managing diabetes and complications. The study participants were recruited by flyers placed in Hispanic markets and in ambulatory care clinics. A total of 34 Hispanic male and female subjects with type 2 diabetes participated in the study. The concentrations of glucose, insulin, hemoglobin A1c (HbA1c), total cholesterol, triglycerides, low-density lipoprotein and high-density lipoprotein (HDL) cholesterol were analyzed at baseline and at 3 months.

RESULTS

A significant mean change was observed for HbA1c, fasting plasma glucose, cholesterol/HDL ratio, and HDL after 3 months of education compared with baseline. There were significant reductions in weight, total fat, percent fat, trunk fat, and waist-to-hip ratio compared with baseline. After 3 months, subjects showed a significant positive correlation between changes in body mass index and insulin and weight, total fat, trunk fat, and fat free mass and insulin.

CONCLUSIONS

A culturally sensitive program conducted in Spanish had a significant impact on important clinical parameters in Hispanic subjects with diabetes in a relatively short time period. The study demonstrates the importance of designing education intervention studies that are sensitive to cultural diversity, particularly in at-risk diabetic subjects.

Insulin resistance, hyperinsulinemia, and hypertension: an epidemiologic approach

During the past 2 decades, numerous experimental studies have provided solid evidence for the existence of several mechanisms connecting insulin resistance and hyperinsulinemia with blood pressure elevation, within the context of the cardiometabolic syndrome. In parallel, several groups have attempted to examine these associations from an epidemiologic perspective, but relevant findings were less consistent and not extensively discussed. Hyperinsulinemia has been associated with high blood pressure levels and hypertension development in cross-sectional, case-control, and prospective cohort studies. An association between insulin resistance and hypertension is also evident in existing studies, but prospective data on this relation are limited. Moreover, most of the evidence supporting close associations between these factors derives from Caucasian and Japanese populations, whereas data in other populations are not in agreement. This review summarizes and evaluates the relevant epidemiologic evidence to elucidate an important aspect of the relationship between hypertension and the cardiometabolic syndrome.

The Pregnancy in Polycystic Ovary Syndrome study: baseline characteristics of the randomized cohort including racial effects

OBJECTIVE

To report the baseline characteristics and racial differences in the polycystic ovary syndrome (PCOS) phenotype from a large multicenter clinical trial (PPCOS).

DESIGN

Double-blind, randomized trial of three treatment regimens (with extended release metformin or clomiphene citrate).

SETTING

Academic medical centers.

PATIENT(S)

Six hundred twenty-six infertile women with PCOS, aged 18-39 years, with elevated T levels and oligomenorrhea (exclusion of secondary causes), seeking pregnancy, with > or = 1 patent fallopian tube, normal uterine cavity, and a partner with sperm concentration > or = 20 x 10(6)/mL in > or = 1 ejaculate.

INTERVENTION(S)

Baseline characterization.

MAIN OUTCOME MEASURE(S)

Historical, biometric, and biochemical measures of PCOS.

RESULT(S)

There were no significant differences in baseline variables between treatment groups. The overall mean (+/-SD) age of the subjects was 28.1 +/- 4.0 years, and the mean body mass index was 35.2 kg/m2 (+/-8.7). Polycystic ovaries (PCOs) were present in 90.3% of the subjects, and the mean volume of each ovary was 10 cm3 or more. Of the subjects, 7% had ovaries that were discordant for PCO morphology. At baseline, 18.3% of the subjects had an abnormal fasting glucose level (> 100 mg/dL). Asians tended to have a milder phenotype, and whites and African Americans were similar in these measures.

CONCLUSION(S)

The treatment groups were well matched for baseline parameters, and we have added further information to the PCOS phenotype.

Characterization of type 2 diabetes mellitus in first generation Italian migrants to Belgium

Type 2 diabetes mellitus is a major metabolic disease in developed countries, and preferentially affects low-income groups and/or people from Southern extraction. Migrants are especially at risk. In Belgium, a large population of workers emigrated in the 50s and 60s, especially from rural areas of Southern Italy and Sicily. We tested the hypothesis that type 2 diabetes mellitus' phenotype in these Italian migrants could differ from that observed in autochthonous Belgian subjects. We retrospectively compared the clinical files of 485 patients with type 2 diabetes either of Belgian (n=445) or Italian origin (n=40). Italians were younger at diagnosis (46 +/- 14 vs. 52 +/- 13 years, P < 0.01), shorter, had a lower education and a stronger family record of diabetes (89 vs. 47%, P < 0.01). They had similar BMIs (31 +/- 6) and similar or slightly worse degree of sedentarity (>75%). We further compared this Italian group to 115 Belgians subjects matched for age, sex, and education. Known duration of diabetes (16 years), smoking and drinking habits, use of oral hypoglycaemic, antihypertensive and hypolipaemic drugs, complications, CRP, estimated glomerular filtration rate, micro-albuminuria prevalence, blood pressure, insulin sensitivity/ beta-cell function estimated by HOMA modelling, as well as fat mass indirectly estimated by impedancemetry were not significantly different between the two populations. There was a non significant trend toward higher HbAlc (8.7 +/- 2 vs. 8.2 +/- 2%, NS) in Italian subjects whose LDL-cholesterol was however significantly lower (105 +/- 31 vs. 120 +/- 33 mg.dL-1, P < 0.01) as well as folic acid (5 + 1.7 vs. 6.7 +/- 4, P < 0.001). Insulin dose was higher (0.77 +/- 0.4 vs. 0.48 +/- 0.3 IU.day-1, P < 0.001) and abdominal obesity less prevalent in males (33 vs. 58%, P < 0.01) of this group. Thus, Italian diabetic subjects in Belgium exhibit higher insulin requirements despite similar/better BMI, known duration of diabetes, HOMA indices, use of oral antidiabetic drugs, abdominal obesity and slightly higher HbA1c. This points towards different dietary habits, as do the differences in folic acid and LDL-cholesterol; different patterns of exercise may also play a role. Higher family record of diabetes may be genetic, but may also be biased by tighter family structure in subjects of Italian extraction.

The metabolic syndrome in Chinese, Malays and Asian Indians. Factor analysis of data from the 1998 Singapore National Health Survey

We used factor analysis to define and compare the manner in which the various features of the metabolic syndrome are linked or clustered in Chinese, Malays and Asian Indians. One thousand nine hundred and fifty seven men (1324 Chinese, 391 Malays and 261 Asian Indians) and 2308 women (1622 Chinese, 391 Malays and 296 Asian Indians) were examined. Anthropometry, blood pressure, serum glucose, lipid concentrations, and serum insulin were measured for all subjects. These data were then subjected to factor analysis which reduced the variables examined to three factors in all ethnic groups and both genders. The first (dyslipidemia) factor was positively loaded for obesity, insulin resistance (IR), fasting triglyceride and negatively loaded for HDL-cholesterol. The second (hyperglycemia) factor was positively loaded for IR and blood glucose. The third (hypertension) factor was positively loaded for obesity and blood pressure. IR was positively loaded in the hypertension factor in Malay women but not in others. Rather than a single entity causally associated with insulin resistance (IR), our findings support a concept in which the metabolic syndrome represents several distinct entities (dyslipidemia, hypertension and hyperglycemia). It appears that Malay females may be more prone to develop hypertension in association with IR.

Metabolic effects of combined antihypertensive treatment in patients with essential hypertension

Single-drug treatment of essential hypertension (HT) is often insufficient to normalize blood pressure (BP), and high doses of antihypertensive agents can have adverse effects on glucose tolerance (GT) and insulin sensitivity. This study tested whether aggressive BP lowering with combination treatment had any influence on GT or insulin action. In all, 29 nonobese (body mass index [BMI], <30 kg/m ), normolipidemic patients with established HT (159 +/- 3/99 +/- 1 mm Hg) but normal GT were recruited. Eleven normotensive (125 +/- 3/85 +/- 1 mm Hg) subjects were matched to the patients for both anthropometric and metabolic variables. Following baseline studies (serum lipid profile, oral GT, insulin release, and insulin sensitivity assessed by the insulin clamp technique), patients were randomized in a double-blind fashion to two combination regimens (verapamil 180 mg/day + trandolapril 2 mg/day or atenolol 50 mg/day + nifedipine 20 mg/day) and restudied 3 months later. Blood pressure was normalized in both groups (with decrements of 25 +/- 5/17 +/- 2 and 29 +/- 3/15 +/- 2 mm Hg, respectively). Lipid profile, GT, insulin release, and insulin sensitivity of both glucose uptake and lipolysis were unchanged following both treatments. The authors conclude that in nonobese, normolipidemic, glucose-tolerant hypertensive patients, BP normalization with combination therapy is feasible at no cost in terms of undesired effects on glucose and lipid metabolism and insulin sensitivity.

Alcohol reduces insulin-hypertension relationship in a general population: the Hisayama study

Insulin resistance may be a factor in the etiology of hypertension, and habitual alcohol intake may modify this relationship. We prospectively examined this hypothesis in 1,133 nonhypertensive, nondiabetic Japanese subjects, aged 40-79 years. Alcohol drinkers were more frequent among men than women at baseline (57.7 vs. 8.2%). The age-adjusted incidence of hypertension significantly increased with the elevating baseline insulin levels in women (P =.003 for trend), but not in men. The age- and sex-adjusted insulin levels and insulin resistance index decreased with elevating alcohol intake, while fasting glucose levels remained unchanged, suggesting that alcohol improves insulin sensitivity. Among nondrinkers, the age-adjusted incidence of hypertension significantly increased with elevating insulin tertiles in both sexes (P =.048 and.002 for trend in men and women, respectively), but not among drinkers. Our findings suggest a close association between insulin resistance and the incidence of hypertension in Japanese. However, alcohol modified and reduced this relationship.

Essential hypertension of Caribbean Hispanics: sodium, renin, and response to therapy

Little is known about essential hypertension in Hispanic Americans, despite the fact that they are the fastest-growing minority in the United States and have a disproportionate degree of hypertensive target organ damage. The authors studied 89 Caribbean Hispanic hypertensive patients who participated in six double-blind, randomized trials of antihypertensive agents. Demographics, laboratory data, sodium excretion, plasma renin activity, and atrial natriuretic peptide were obtained after 3-4 weeks on placebo. Blood pressure responses to angiotensin-converting enzyme (ACE) inhibitors, beta blockers, calcium channel blockers, hydrochlorothiazide (HCTZ), and fixed combinations of ACE inhibitors and HCTZ, were compared to the placebo values after 8-12 weeks of treatment. Patients had a multiple risk factor profile (obesity and diabetes) and a wide spectrum of blood pressure elevation, left ventricular hypertrophy, and hypertensive renal damage. Urine sodium excretion rates indicated inability to comply with salt restriction in 65% of patients. Plasma renin activity was lower than that of Hispanic normotensive controls, and 62% of patients had low-renin essential hypertension by renin profiling to sodium excretion. On analysis of variance, blood pressure reductions by calcium channel blockers, HCTZ, and ACE inhibitor/HCTZ combinations were significantly greater than that with placebo, while those of ACE inhibitors and beta blockers as monotherapy were not. The authors conclude that essential hypertension of Caribbean Hispanics is associated with multiple risk factors and is largely of the low-renin type. Responses to therapy are consistent with those observed in other populations with the low-renin phenotype and suggest salt-sensitivity of blood pressure in this population. Confirmation of the latter has implications for prevention and treatment of essential hypertension in Hispanics.

Clinical, biophysical and biochemical variables from African-heritage subjects with type 2 diabetes

We compared the metabolic profile of two ethnic populations with type 2 diabetes, one from Bantu (n = 23; Ban) and the other from Belgian (n = 314) extraction followed at St Luc Hospital. Further comparison with a Belgian sub-cohort (n = 64; Be) matched for age (52 yrs) and sex distribution (M/F: 61/39%) showed no significant difference between Belgian and Bantu subjects with regards to diabetes duration (9 and 11 yrs; Ban and Be respectively), age at diabetes diagnosis (43 and 42 yrs), HbA1c (8.1 +/- 1.9 vs. 8.5 +/- 1.9%; NS), and achieved education level. BMI was lower in Ban (29 +/- 4 vs. 32 +/- 7 in Be; p < 0.02), as were body fat (33 +/- 12 vs. 37 +/- 11 kg; NS) and waist diameter (99 +/- 9 vs. 106 +/- 16 cm; p < 0.02). Forty-eight and 72% of Ban and Be were on metformin (p < 0.05), while insulin was given to 39 and 34%. Daily insulin dose was lower in Ban (0.31 +/- 0.20 vs. 0.47 +/- 0.18 IU.kg-1.24 h-1; p < 0.001). There was no difference in beta-cell function (% beta; normal: 100%) or insulin sensitivity (%S; normal: 100%) as determined with HOMA between groups. % beta (median [perc 25-75]) was 51 [23-119] and 67 [45-84] in Ban and Be, while %S was 32 [29-37] and 37 [27-45]. Smoking (past & current) prevalence was 5 and 47% in Ban and Be (p < 0.0001). Prevalence of micro- and macroangiopathy did not differ between groups, although Ban had more macroalbuminuria (29 vs. 9%; p < 0.05), and were more often treated with Ca(2+)-channel- and beta-blockers than Be subjects (36 and 39% vs. 16 and 8%; p = 0.07 and < 0.05, respectively). Fasting (F) and interprandial (IP) triglycerides (TG) were lower in Ban: 115 [81-149] vs. 189 [155-325] mg.dL-1 for F-TG and 127 [81-160] vs. 170 [128-305] mg.dL-1 for IP-TG (p < 0.0001), as was total cholesterol (201 +/- 53 vs. 223 +/- 40 mg.dL-1 (p < 0.05), despite lower use of hypolipidaemic drug (13 vs. 44%; p < 0.01). African-heritage subjects with type 2 diabetes have similar degree of diabetes control and complications, in the presence of leaner biophysical status, minimal tobacco exposure and lower fasting and interprandial triglycerides.

Obesity and cardiovascular disease. Pathogenetic role of the metabolic syndrome and therapeutic implications

Since obesity is a major risk factor for cardiovascular disease (CVD), the increasing prevalence and degree of obesity in all developed countries has the potential to significantly offset the current efforts to decrease CVD burden in our population. Obesity is pathogenetically related to several clinical and sub-clinical abnormalities that contribute to the development of atherosclerotic placks and their complication, leading to the onset of cardiovascular events. Obesity seems to interact with inheritable factors in determining the onset of insulin resistance, a metabolic abnormality that is responsible for altered glucose metabolism and predisposition to type 2 diabetes, but that also has a major role in the development of dyslipidemia, hypertension and many other sub-clinical abnormalities that contribute to the atherosclerotic process and onset of cardiovascular events. Inheritable factors seem to modulate the onset of type 2 diabetes, dyslipidemia, hypertension and various insulin resistance-related sub-clinical abnormalities, often in a clustering pattern that is commonly referred to as the "metabolic syndrome." Inheritable factors also are involved in the onset of CVD in a given population or individuals with various components of the metabolic syndrome. Intense research is currently undergoing to better understand the molecular mechanisms that could explain the relationship between environmental and inheritable factors that lead from obesity to atherosclerosis and cardiovascular event. The elucidation of these mechanisms will provide improved therapeutic strategies to reduce cardiovascular risk in the obese patients. However, effective therapeutic tools that control each of the known pathophysiological steps mediating CVD in obese patients are already available and should be used more aggressively. Patient education and coordinated approach of physicians, nurses and other health care providers in a multidisciplinary treatment of the obese patient is of fundamental importance to reduce CVD burden in our population.

Weight loss is correlated with an improved lipoprotein profile in obese postmenopausal women

BACKGROUND

Changes in plasma lipid and lipoprotein distributions that occur after menopause increase the risk of cardiovascular disease in women, especially in those who are overweight.

OBJECTIVE

The purpose of this study was to evaluate the impact of a nine-month weight reduction program on plasma lipids, dietary intake and abdominal fat obesity.

DESIGN

A partial crossover design was used to study a weight loss treatment consisting of Phentermine hydrochloride (Fastin, SmithKline Beecham Pharmaceuticals, Philadelphia, PA) therapy plus a low energy diet (5040 kJ/d). Forty-seven obese, postmenopausal Caucasian women (BMI of 30-38 kg/m2) were randomized into two groups, both of which received drug and diet treatment over six months. However, Group I started the intervention program three months later than Group II. Plasma total, HDL and LDL cholesterol and triacylglycerol were measured, body composition was assessed by anthropometry and dual energy x-ray absorptiometry, and food frequency records were collected at four timepoints.

RESULTS

Over nine months, women in Group II reduced body weight (14.4%), lowered plasma concentrations of LDL cholesterol (14% to 26%) and triacylglycerol (15%) and raised plasma HDL cholesterol concentration (15%). These plasma lipid changes decreased the total cholesterol/HDL cholesterol ratio from 4.3 to 3.2. All subjects decreased abdominal fat measurements and energy and cholesterol intakes, as well as percentage of energy derived from total and saturated fat during the study. Most subjects also increased dietary fiber consumption.

CONCLUSION

Both weight loss and diet modifications are associated with an improved plasma lipid profile in obese postmenopausal women.

Elevated fasting insulin predicts incident hypertension: the ARIC study. Atherosclerosis Risk in Communities Study Investigators

OBJECTIVE

The prospective association of insulin and hypertension has been under debate in the context of the development of the insulin resistance or multiple metabolic syndrome. We examined the predictive associations of fasting serum insulin with incident hypertension occurring alone or as part of the multiple metabolic syndrome.

DESIGN

Analyses were restricted to 5221 middle-aged participants of the Atherosclerosis Risk in Communities Study cohort who were free of component disorders of the multiple metabolic syndrome (hypertension; diabetes; high triglycerides and/or low HDL cholesterol (dyslipidaemias)) at baseline.

OUTCOME

A total of 1018 individuals developed hypertension, 801 in the absence of components of the metabolic syndrome and 217 in combination with diabetes or dyslipidaemias, between 1987 and 1993.

RESULTS

Elevated fasting insulin (top quartile versus lowest quartile) was associated with overall incident hypertension in European Americans [hazard rate ratio (HRR) 2.0, 95% confidence interval (CI) 1.7-2.4] but the results were inconclusive in African Americans (HRR 1.3, 95% CI 0.9-1.8) after adjustment for age, gender and study centre. Among European Americans, body mass index and abdominal girth only partly explained the observed association. Elevated fasting insulin was more strongly predictive of hypertension occurring as a component of the multiple metabolic syndrome (HRR 2.4, 95% CI 1.5-3.9) than of hypertension occurring alone (HRR 1.3, 95% CI 1.0-1.7) adjusting statistically for age, gender, study centre, body mass index and abdominal girth.

CONCLUSIONS

The results are consistent with the concept of an aetiological heterogeneity for hypertension and may explain previously reported inconsistent findings on the association of insulin with incident hypertension.

Salt sensitivity: concept and pathogenesis

Almost two decades ago, the existence of a subset of essential hypertensive patients, who were sensitive (according to the increase in blood pressure levels) to the intake of a diet with a high salt content, was described. These patients are characterized by an increase in blood pressure and in body weight when switched from a low to a high sodium intake. The increase in body weight is due to the incapacity of the kidneys to excrete the whole intake of sodium until renal perfusion pressure (mean blood pressure) attains a level that is able to restore pressure-natriuresis relationship to values that enable the kidney to excrete the salt ingested or administered intravenously. Salt sensitivity does not seem to depend on the existence of an intrinsic renal defect to handle sodium, but on the existence of subtle abnormalities in the regulation of the sympathetic nervous system, the renin-angiotensin system or endothelial function. It is also relevant that organ damage secondary to arterial hypertension, has been shown in animal models and in hypertensive humans sensitive to a high salt intake to be significantly higher when compared with that of salt-resistant animals or humans. Interestingly, in humans, salt sensitivity has been shown to correlate with microalbuminuria, an important predictor of cardiovascular morbidity and mortality, which correlates with most of the cardiovascular risk factors commonly associated with arterial hypertension. One of these factors is insulin resistance, that usually accompanies high blood pressure in overweight and obese hypertensives. Insulin resistance and hyperinsulinism are present in a significant percentage of hypertensive patients developing cardiovascular symptoms or death. For these reasons, therapy of arterial hypertension must be directed, not only to facilitate the lowering of BP level, but also, to halt the mechanisms underlying the increase in BP, when salt intake is increased. Furthermore, therapy must preferably improve the diminished insulin sensitivity present in salt-sensitive subjects that contribute independently to increased cardiovascular risk.

Response of insulin, glucagon, lactate, and nonesterified fatty acids to glucose in visceral obesity with and without NIDDM: relationship to hypertension

Insulin, glucagon, glucose, nonesterified fatty acids (NEFA), and lactate response to oral glucose tolerance test (OGTT, 75 g glucose) and their correlation with mean blood pressure (BP), were studied in 10 normal subjects (N), 25 subjects with abdominal obesity (O), and 9 subjects with abdominal obesity and IGT or non-insulin-dependent diabetes (OD). O and OD patients, as compared to N subjects, showed increased fasting NEFA, lactate, insulin, and glucagon. NEFA area and insulin total and incremental areas were increased in O and OD (P < 0.001 in all instances). Glucagon total areas were increased only in OD (P < 0.01). Lactate total areas were increased in O (P < 0.001) and in OD (P < 0.01), while lactate incremental area was diminished in O and, even more, in OD subjects (P < 0.001 in both instances) and was inversely correlated with the basal level (P < 0.001). In all subjects as a whole, increase in NEFA area was weakly correlated with total and incremental insulinemic areas (P < 0.05) and more strongly correlated with glucagon and lactate areas (P < 0.01). Conversely, the incremental areas of lactate were negatively correlated with total insulin (P < 0.05), NEFA (P < 0.05), and glucagon (P < 0.001) areas. BP was increased in O (103.62 +/- 2.37) and, even more, in OD (109.41 +/- 5.22) compared to that seen in N (92.55 +/- 0.94 mm Hg), with P < 0.01, and was correlated with fasting insulin (P < 0.01) and glucose (P < 0.05) and, even more, with total (P < 0.001) and incremental (P < 0.01) insulin areas and NEFA areas (P < 0.001). Conversely, BP also was negatively correlated with incremental lactate area (P < 0.01) (similarly to insulin and NEFA area). Our data would suggest that in O and OD patients, insulin resistance is associated with elevated NEFA, insulin and glucagon as well as with high BP. since NEFA are inhibitors of Na,K-ATPase, they could contribute to elevate BP through the repression of this enzyme (which we have shown previously to be reduced in adipose tissue of obese subjects and correlated negatively with BP.

Progress in population analyses of the insulin resistance syndrome

Insulin resistance is associated with a variety of cardiovascular risk factors including hypertension, dyslipidemia, and non-insulin-dependent diabetes. In blacks, the relation between insulin resistance, hypertension, and atherosclerosis has been questioned. Most data collected on the Insulin Resistance Syndrome have been collected in nondiabetic subjects; therefore, no inference can be drawn to exogenous insulin use in diabetic subjects where improved glycemic control is usually associated with improved cardiovascular risk factors (especially dyslipidemia) in the absence of weight gain.

Insulin resistance and hypersecretion in obesity. European Group for the Study of Insulin Resistance (EGIR)

Insulin resistance and insulin hypersecretion are established features of obesity. Their prevalence, however, has only been inferred from plasma insulin concentrations. We measured insulin sensitivity (as the whole-body insulin-mediated glucose uptake) and fasting posthepatic insulin delivery rate (IDR) with the use of the euglycemic insulin clamp technique in a large group of obese subjects in the database of the European Group for the Study of Insulin Resistance (1,146 nondiabetic, normotensive Caucasian men and women aged 18-85 yr, with a body mass index (BMI) ranging from 15 to 55 kg.m-2). Insulin resistance, defined as the lowest decile of insulin sensitivity in the lean subgroup (608 subjects with a mean BMI of 29 kg.m-2). Insulin sensitivity declined linearly with BMI at an age- and sex-adjusted rate of 1.2 micromol.min-1.kg FFM-1 per BMI unit (95% confidence intervals = 1.0-1.4). Insulin hypersecretion, defined as the upper decile of IDR, was significantly (P<0.0001) more prevalent (38%) than insulin resistance in the obese group. In the whole dataset, IDR rose as a function of both BMI and insulin resistance in a nonlinear fashion. Neither the waist circumference nor the waist-to-hip ratio, indices of body fat distribution, was related to insulin sensitivity after adjustment for age, gender, and BMI; both, however, were positively associated (P<0.001) with insulin hypersecretion, particularly in women. In nondiabetic, normotensive obese subjects, the prevalence of insulin resistance is relatively low, and is exceeded by the prevalence of insulin hypersecretion, particularly in women with central obesity. In the obese with preserved insulin sensitivity, risk for diabetes, cardiovascular risk, and response to treatment may be different than in insulin resistant obesity.

Epidemiology of hypertension and insulin resistance syndrome

INSULIN RESISTANCE SYNDROME: Insulin resistance syndrome (syndrome X) indicates that insulin resistance is associated with and may be the cause of several metabolic conditions including hypertension, dyslipidemia, non-insulin dependent diabetes mellitus (NIDDM).

HYPERTENSION

Although the association between insulin resistance and hypertension remains somewhat controversial, hypertensive subjects are clearly at increased risk of developing NIDDM. Insulin concentrations are a relatively weak predictor of the development of hypertension. It is possible that the relation between insulin, blood pressure and atherosclerosis may be weaker in blacks. However, antihypertensive agents that worsen insulin resistance may further increase the risk of NIDDM already present in subjects with hypertension.

Effects of losartan on insulin sensitivity in hypertensive subjects

Losartan, the first specific and orally available angiotensin II receptor antagonist, is a potent antihypertensive drug with a low incidence of side effects in humans. However, the effects of losartan on insulin sensitivity and glucose metabolism have not been investigated in detail. Therefore, we carried out a randomized, double-blind study to compare the effects of losartan (50 mg QD) and metoprolol (95 mg QD) on insulin sensitivity, insulin secretion, glucose tolerance, and lipids and lipoproteins in 20 hyperinsulinemic subjects with essential hypertension. The fall in blood pressure was greater with losartan than with metoprolol. Insulin sensitivity evaluated by the euglycemic clamp technique did not change in either group after 12 weeks of treatment. Similarly, glucose oxidation (losartan: 17.0 +/- 0.9 versus 16.9 +/- 1.0 mumol/kg per minute [before versus after, P = NS]; metoprolol: 17.9 +/- 1.3 versus 16.8 +/- 1.6 [P = NS]) and nonoxidation (losartan: 22.3 +/- 4.0 versus 23.5 +/- 3.4 mumol/kg per minute [P = NS]; metoprolol: 23.3 +/- 3.2 versus 25.6 +/- 4.7 [P = NS]) remained unchanged during the last 30 minutes of the 3-hour euglycemic clamp. Losartan and metoprolol did not have any significant adverse effects on insulin secretion, glucose tolerance, or lipids and lipoproteins. In conclusion, losartan is metabolically neutral, without any significant adverse effect on glucose and lipid metabolism.

Cardiovascular risk factors and the prediabetic syndrome

Cardiovascular disease is increased 2- to 4-fold in non-insulin-dependent diabetes mellitus (NIDDM); yet in most studies, there is a relatively weak relationship between the frequency of coronary heart disease (CHD) and the duration of diabetes and severity of hyperglycaemia. A number of authors have suggested that the prediabetic stage may contribute to the risk of CHD in NIDDM. Hyperinsulinaemia and insulin resistance have been strongly associated with the development of NIDDM. Data are less conclusive about the relationship of hyperinsulinaemia to the development of CHD in nondiabetic subjects. Relatively little data are available on hyperinsulinaemia and/or insulin resistance to CHD in NIDDM subjects. Tight control of glycaemia with exogenous insulin improves cardiovascular risk factors in NIDDM subjects and therefore is unlikely to increase the risk of CHD. Although the relation of insulin to CHD in the general population is somewhat controversial, insulin is clearly related to multiple cardiovascular risk factors (especially elevated triglyceride, decreased high-density lipoprotein, small dense low-density lipoprotein, impaired glucose tolerance and increased plasminogen activator inhibitor 1 (PAI-1)). However, the relation of insulin resistance to hypertension remains controversial.

Suboptimal outcome of management of metabolic cardiovascular risk factors in Hispanic patients with essential hypertension

We studied outcome of management of metabolic cardiovascular risk factors in 155 randomly chosen Hispanic hypertensive patients (mean age, 63 +/- 1 years; 79% female) screened for dyslipidemia. Hypertriglyceridemia (n = 12) or high risk-adjusted low-density lipoprotein cholesterol (LDL-C) (n = 89) was found in 65%. Triglycerides did not change (6.16 +/- 0.58 to 7.44 +/- 2.34 mmol/L; P = NS) over 2.2 +/- 0.5 years. Only 58 patients with high LDL-C were treated, and 8 had no follow-up lipid tests. In the other 50, LDL-C decreased by 10 +/- 3% (P < .001) over 2.8 +/- 0.2 years but attained goal in only 12. In a subset of 24 patients with extended follow-up (3.8 +/- 0.2 years), there was an initial marked decline in LDL-C, followed by a rebound to baseline levels. In 29 of 54 patients with normal LDL-C, lipid testing was markedly overused compared with recommendations. Obesity (n = 94, 61%) did not improve in those with repeated data (+0.6 +/- 0.8 kg; P = NS; n = 40) over 2.7 +/- 0.3 years. Forty-four of 63 patients with type II diabetes had repeated measurement of glycosylated hemoglobin, with no change (10.5 +/- 0.5% to 11.2 +/- 0.5%; P = NS) over 2.2 +/- 0.3 years. Ten-year risk of coronary events (Framingham cohort parametric regression) calculated for 61 patients with known untreated blood pressures (169 +/- 3/98 +/- 1 mm Hg) was 21.0 +/- 1.7%, with a skewed distribution reaching high values (66%) and attributable in large part (72%) to modifiable risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin resistance in microalbuminuric hypertension. Sites and mechanisms

Microalbuminuria in patients with essential hypertension is a marker of incipient glomerular dysfunction and clusters with lipid and hemodynamic abnormalities. Recent evidence has shown that hypertensive patients with microalbuminuria have a hyperinsulinemic response to oral glucose, suggesting the presence of insulin resistance. To directly test this possibility we studied insulin action in two accurately matched groups (n = 10 each) of hypertensive patients with or without microalbuminuria (14 +/- 2 versus 52 +/- 7 mg/24 h-1, mean of three 24-hour collections). In response to glucose ingestion microalbuminuric patients showed slight hyperglycemia (area under the curve, 928 +/- 43 versus 784 +/-19 nmol/L-1/2h-1, P < .02) and a marked hyperinsulinemia (26.8 +/- 3.3 versus 49.8 +/- 3.7 nmol/L-1/2h-1, P < 0.01). Basal arterial blood pressure, heart rate, and forearm blood flow were similar in the two groups and did not change significantly during a 2-hour euglycemic insulin clamp. Insulin-stimulated wholebody glucose uptake was 25% lower in microalbuminuric patients (33.5 +/- 2.5 versus 25.2 +/- 2.1 mumol/min-1/kg-1, P < .02). This difference was entirely due to a 40% reduction in glycogen synthesis (12.9 +/- 1.8 versus 21.3 +/- 3.2 mumol/min-1/kg-1, P < .05) as glucose oxidation was similarly stimulated in the two groups. In contrast there was no difference in the ability of insulin to suppress hepatic glucose production (by approximately 100% at the end of the clamp), to decrease fractional sodium and potassium excretions (by 35%), to lower circulating free fatty acids (by 80%), and to reduce plasma potassium concentrations (by 10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Renal failure among male Hispanics in the United States

This study examined epidemiologic patterns and time trends among male patients with Hispanic surnames in the Medicare End-Stage Renal Disease Program and compared US Hispanics with non-Hispanic Blacks and Whites. Male Hispanics had substantially higher proportions of end-stage renal disease attributed to diabetes than did Blacks and Whites. There were notable regional differences among Hispanics. Between 1980 and 1990, the incidence of treated renal failure among Hispanics increased more than that among Blacks or Whites. The increasing number of Hispanics in the United States with end-stage renal disease emphasizes the importance of explicit health evaluations and prevention strategies for Hispanic populations.

Fasting plasma insulin level is an important risk factor for the development of complications in Japanese obese children--results from a cross-sectional and a longitudinal study

It is not known what types of factors may contribute to the development of complications in obese children. In the current investigation, we have performed a cross-sectional and a longitudinal study in Japanese obese children to clarify the relationship of the extent of obesity, fat distribution, insulin resistance, and aging to the development of obesity-related complications. In the cross-sectional study of 329 obese boys and 142 obese girls aged 7 to 15 years, the fasting plasma immunoreactive insulin (IRI) level was significantly higher than that of 46 non-obese boys and 48 non-obese girls (boys, 13.4 +/- 6.7 v 4.9 +/- 1.9 microU/mL, P < .001; girls, 14.0 +/- 5.9 v 4.8 +/- 1.8, P < .001). Linear regression analysis demonstrated that fasting plasma IRI correlated positively with fasting plasma glucose (FPG), triglycerides (TG), uric acid (UA), and systolic blood pressure (SBP) in obese boys, and with TG, SBP, and diastolic blood pressure (DBP) in obese girls, and negatively with serum high-density lipoprotein cholesterol (HDL-C) in both obese boys and girls. Multiple regression analysis demonstrated that fasting plasma IRI was independently and positively correlated with FPG, TG, and SBP in obese boys. Fasting plasma IRI in obese girls was positively correlated with TG, SBP, and DBP, and negatively with HDL-C. FPG decreased significantly in non-obese children at the onset of puberty, but it remained unchanged in obese children. Fasting plasma IRI and the IRI to glucose ratio increased with age in obese children, whereas they did not show any significant changes in non-obese children.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose and insulin levels during diuretic therapy in hypertensive men

We investigated serum glucose and insulin levels resulting from thiazide or thiazide-like diuretic administration and determined whether they were associated with serum or intracellular potassium or magnesium values. We also explored the role of obesity both alone and with thiazides on serum insulin and glucose. Hypertensive men were withdrawn from diuretics and repleted with oral potassium and magnesium and then randomized to 2 months of treatment with (1) hydrochlorothiazide, (2) hydrochlorothiazide with oral potassium, (3) hydrochlorothiazide with oral potassium and magnesium (4) hydrochlorothiazide and triamterene, (5) chlorthalidone, or (6) placebo. Serum was available from 202 participants for insulin and glucose determinations. Mean fasting serum glucose and insulin did not change significantly after 2 months of randomized therapy with the exception of participants randomized to chlorthalidone, who had significant increases in both serum insulin and glucose (P < .05 and P < .01, respectively). As body mass index increased, there was a corresponding increase in serum insulin and to a lesser degree in serum glucose. Also, as body mass index increased, participants taking hydrochlorothiazide had a corresponding increase of serum insulin (P < .05). After treatment, intracellular potassium and magnesium were both associated with higher serum insulin (P < .001 for each), and serum potassium was associated with higher and serum magnesium with lower serum glucose (P < .01 for each). In most hypertensive men, treatment with 50 mg chlorthalidone increases glucose and insulin levels, whereas administration of 50 mg hydrochlorothiazide, with or without potassium and/or magnesium conserving strategies, does not.(ABSTRACT TRUNCATED AT 250 WORDS)

Is hyperinsulinaemia a central characteristic of a chronic cardiovascular risk factor clustering syndrome? Mixed findings in Asian Indian, Creole and Chinese Mauritians. Mauritius Noncommunicable Disease Study Group

The aim of the study was to investigate whether the constellation of cardiovascular disease risk factors, described as Insulin Resistance Syndrome, exists in the multi-ethnic population of Mauritius, and to assess whether hyperinsulinaemia is the key feature of this syndrome. A sample of 5080 Mauritian subjects (aged 25-74 years) was examined in a noncommunicable diseases survey in 1987. Survey procedure included an oral glucose tolerance test, and anthropometric, blood pressure, plasma lipids and serum insulin measurements. Abnormal glucose tolerance (diabetes and impaired glucose tolerance), general obesity, upper-body obesity, hypertension, low HDL-cholesterol, and hypertriglyceridaemia were defined as risk factor conditions. Mean values for a series of risk factor variables were compared between reference subjects (no risk factors) and those with a risk factor condition (either one condition only, or in combination with one or more others). Prevalence estimates for each risk factor condition in combination with three or more other conditions were three to four times greater than expected by chance, and levels of risk factors for subjects with more than one risk factor condition were further away from the reference levels than for those with just one condition. Fasting and 2-h serum insulin levels were elevated for each condition when in combination with others, or to a lesser extent when isolated. However, this was not the case for isolated hypertension where insulin levels were not elevated. When adjusted for age, sex, and body mass index, insulin levels were only significantly elevated in subjects with upper-body obesity if in association with general obesity.(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin and hypertension: are they related?

It has been postulated that insulin resistance and the concomitant compensatory hyperinsulinemia contribute to the pathogenesis of hypertension, possibly by stimulating the sympathetic nervous system, promoting renal sodium reabsorption, modulating cation transport, and/or stimulating vascular smooth muscle hypertrophy. The purpose of this article is to present a comprehensive up-to-date review of the literature and critically examine the insulin resistance-hyperinsulinemia-hypertension hypothesis.

Correlation between blood pressure and plasma insulin in acromegaly

OBJECTIVES

The aims of this study were to determine the possible role of hyperinsulinaemia in the increase in blood pressure in acromegalic patients.

DESIGN

After an overnight fast, blood samples were obtained at 0. 30, 60, 120 and 180 min after 75 g glucose ingestion, and plasma growth hormone (GH) and plasma insulin (IRI) were measured by radioimmunoassay. The blood pressure was measured at 10.00 hours for 3 days in a supine position.

SUBJECTS

Nineteen (nine women and 10 men) untreated acromegalic patients, aged 25-69 years.

RESULTS

There were no significant correlations between mean blood pressure (MBP; diastolic+one-third pulse pressure) and basal GH, sum of plasma GH at 0, 30, 60, 120 and 180 min or basal IRI. However, significant correlation was observed between MBP and IRI at 120 min (r = 0.57, P < 0.02) or sum of plasma IRI at 0, 30, 60, 120 and 180 min) (r = 0.58, P < 0.02).

CONCLUSIONS

We conclude that hyperinsulinaemia may be involved in an increase in blood pressure in active acromegalics.