Insulin resistance, hyperinsulinemia, dyslipidemia, hypertension, and accelerated atherosclerosis

Association between insulin resistance and incidence of carotid atherosclerotic plaque: A cohort study

BACKGROUND AND AIMS

There is limited evidence on the association between insulin resistance (IR) and carotid plaque was reported in prospective study. We aimed to exploit the relationship between IR and carotid plaque in a prospective cohort study.

METHODS AND RESULTS

The study was performed in a functional community cohort in urban Beijing. In 2015, a total of 7061 individuals without intima-media thickness (IMT) thickening and carotid artery plaque were recruited and followed up until 2019. Restricted cubic spline was conducted to exploit the dose-response relationship between carotid plaque and baseline HOMA-IR or TyG index as continuous variables. Logistic regression was used to analyze the associations between carotid plaque and HOMA-IR or TyG index. During the average 4 years follow-up, 589 subjects developed carotid plaque. Both HOMA-IR and TyG index showed significant linear dose-response relationship on carotid plaque (p < 0.001). The RRs (95%CI) for subjects with baseline HOMA-IR in quartile 2, quartile 3 and quartile 4 were 1.52 (1.14-2.04), 1.86 (1.40-2.46), and 2.55 (1.94-3.35) compared to quartile 1, respectively. Compared to the first quartile of TyG, the RRs (95%CI) for subjects in quartile 2, quartile 3 and quartile 4 were 1.43 (1.08-1.90), 1.59 (1.20-2.12), and 1.69 (1.26-2.25), respectively. In total population, the predictive ability of HOMA-IR for carotid plaque was significantly better than that of TyG index (p = 0.025).

CONCLUSION

IR is an independent risk factor of carotid plaque. Both HOMA-IR and TyG has significant predictive ability for carotid plaque.

Development of the prediction model for hypertension in patients with idiopathic inflammatory myopathies

Cardiac involvement is an important cause of morbidity and mortality in patients with idiopathic inflammatory myopathies (IIMs). Hypertension, an important cardiovascular risk factor for the general population, has a crucial role in heart involvement. However, few studies have focused on the hypertension associated with IIMs. This study aimed to develop and assess the prediction model for incident hypertension in patients with IIMs. A retrospective cohort study was performed on 362 patients with IIMs, of whom 54 (14.9%) were given a diagnosis of new-onset hypertension from January 2008 to December 2018. The predictors of hypertension in IIMs were selected by least absolute shrinkage and selection operator (LASSO) regression, multivariable logistic regression, and clinically relevance, and then these predictors were used to draw the nomogram. Discrimination, calibration and clinical usefulness of the model were evaluated using the C-index, calibration plot, and decision curve analysis, respectively. The predicting model was validated by the bootstrapping validation. The nomogram mainly included predictors such as age, diabetes mellitus, triglyceride, low-density lipoprotein-cholesterol (LDL-C), antinuclear antibodies (ANA), and smoking. This prediction model demonstrated good discrimination with a C-index of 0.754 (95%CI, 0.684 to 0.824) and good calibration. The C-index of internal validation was 0.728, and decision curve analysis demonstrated that this nomogram was clinically useful. Clinicians can use this prediction model to assess the risk of hypertension in IIMs patients, and early preventive measures should be taken to reduce the incidence of hypertension in high-risk patients.

Developmental programming: Adipose depot-specific changes and thermogenic adipocyte distribution in the female sheep

Prenatal testosterone (T)-treated female sheep exhibit an enhanced inflammatory and oxidative stress state in the visceral adipose tissue (VAT) but not in the subcutaneous (SAT), while surprisingly maintaining insulin sensitivity in both depots. In adult sheep, adipose tissue is predominantly composed of white adipocytes which favor lipid storage. Brown/beige adipocytes that make up the brown adipose tissue (BAT) favor lipid utilization due to thermogenic uncoupled protein 1 expression and are interspersed amidst white adipocytes, more so in epicardiac (ECAT) and perirenal (PRAT) depots. The impact of prenatal T-treatment on ECAT and PRAT depots are unknown. As BAT imparts a metabolically healthy phenotype, the depot-specific impact of prenatal T-treatment on inflammation, oxidative stress, differentiation and insulin sensitivity could be dictated by the distribution of brown adipocytes. This hypothesis was tested by assessing markers of oxidative stress, inflammation, adipocyte differentiation, fibrosis and thermogenesis in adipose depots from control and prenatal T (100  mg T propionate twice a week from days 30-90 of gestation) -treated female sheep at 21 months of age. Our results show prenatal T-treatment induces depot-specific changes in inflammation, oxidative stress state, collagen accumulation, and differentiation with changes being more pronounced in the VAT. Prenatal T-treatment also increased thermogenic gene expression in all depots indicative of increased browning with effects being more prominent in VAT and SAT. Considering that inflammatory and oxidative stress are also elevated, the increased brown adipocyte distribution is likely a compensatory response to maintain insulin sensitivity and function of organs in the proximity of respective depots.

Sodium acetate and androgen receptor blockade improve gestational androgen excess-induced deteriorated glucose homeostasis and antioxidant defenses in rats: roles of adenosine deaminase and xanthine oxidase activities

Nutritional challenges and androgen excess have been implicated in the development of gestational diabetes and poor fetal outcome, but the mechanisms are not well delineated. The effects of short chain fatty acid (SCFA) on glucose dysmetabolism and poor fetal outcome induced by gestational androgen excess is also not known. We tested the hypothesis that blockade of androgen receptor (AR) and suppression of late gestational androgen excess prevents glucose dysmetabolism and poor fetal outcome through suppression of adenosine deaminase (ADA)/xanthine oxidase (XO) pathway. Twenty-four pregnant Wistar rats were treated (sc) with olive oil, testosterone propionate (0.5 mg/kg) singly or in combination with SCFA (sodium acetate; 200 mg/kg; p.o.) or AR blocker (flutamide; 7.5 mg/kg; p.o.) between gestational days 14 and 19. The results showed that late gestational androgen excess led to glucose deregulation, poor fetal outcome, increased plasma and hepatic free fatty acid and lactate dehydrogenase, liver function marker enzymes, malondialdehyde, uric acid, ADA and XO activities. Conversely, gestational androgen excess resulted in reduced body weight gain, visceral adiposity, plasma and hepatic anti-oxidant defenses (glutathione peroxidase, reduced glutathione/glutathione disulphide ratio, glucose-6-phosphate dehydrogenase, adenosine and nitric oxide). However, all these effects were ameliorated by either sodium acetate or flutamide treatment. The study demonstrates that suppression of testosterone by SCFA or AR blockade protects against glucose deregulation and poor fetal outcome by improvement of anti-oxidant defenses and replenishment of hepatic oxidative capacity through suppression of ADA/XO pathway. Hence, utility of SCFA should be encouraged for prevention of glucose dysmetabolism and poor fetal outcome.

Insulin resistance in ischemic stroke

Insulin resistance often refers to a pathological condition in which cells fail to respond to the normal actions of insulin. Increasing literature has noted a critical role of insulin resistance in the pathogenesis of ischemic stroke. Insulin resistance plays an important role in the pathogenesis of ischemic stroke via enhancing advanced changes of atherosclerosis. A variety of literature indicates that insulin resistance enhances platelet adhesion, activation and aggregation which are conducive to the occurrence of ischemic stroke. Insulin resistance also induces hemodynamic disturbances and contributes to the onset of ischemic stroke. In addition, insulin resistance may augment the role of the modifiable risk factors in ischemic stroke and induce the occurrence of ischemic stroke. Preclinical and clinical studies have supported that improving insulin resistance may be an effective measure to prevent or delay ischemic stroke.

Developmental Programming: Impact of Gestational Steroid and Metabolic Milieus on Mediators of Insulin Sensitivity in Prenatal Testosterone-Treated Female Sheep

Prenatal testosterone (T) excess in sheep leads to peripheral insulin resistance (IR), reduced adipocyte size, and tissue-specific changes, with liver and muscle but not adipose tissue being insulin resistant. To determine the basis for the tissue-specific differences in insulin sensitivity, we assessed changes in negative (inflammation, oxidative stress, and lipotoxicity) and positive mediators (adiponectin and antioxidants) of insulin sensitivity in the liver, muscle, and adipose tissues of control and prenatal T-treated sheep. Because T excess leads to maternal hyperinsulinemia, fetal hyperandrogenism, and functional hyperandrogenism and IR in their female offspring, prenatal and postnatal interventions with antiandrogen, flutamide, and the insulin sensitizer rosiglitazone were used to parse out the contribution of androgenic and metabolic pathways in programming and maintaining these defects. Results showed that (1) peripheral IR in prenatal T-treated female sheep is related to increases in triglycerides and 3-nitrotyrosine, which appear to override the increase in high-molecular-weight adiponectin; (2) liver IR is a function of the increase in oxidative stress (3-nitrotyrosine) and lipotoxicity; (3) muscle IR is related to lipotoxicity; and (4) the insulin-sensitive status of visceral adipose tissue appears to be a function of the increase in antioxidants that likely overrides the increase in proinflammatory cytokines, macrophages, and oxidative stress. Prenatal and postnatal intervention with either antiandrogen or insulin sensitizer had partial effects in preventing or ameliorating the prenatal T-induced changes in mediators of insulin sensitivity, suggesting that both pathways are critical for the programming and maintenance of the prenatal T-induced changes and point to potential involvement of estrogenic pathways.

Interaction between Marine-Derived n-3 Long Chain Polyunsaturated Fatty Acids and Uric Acid on Glucose Metabolism and Risk of Type 2 Diabetes Mellitus: A Case-Control Study

The present case-control study explored the interaction between marine-derived n-3 long chain polyunsaturated fatty acids (n-3 LC PUFAs) and uric acid (UA) on glucose metabolism and risk of type 2 diabetes mellitus (T2DM). Two hundred and eleven healthy subjects in control group and 268 T2DM subjects in case group were included. Plasma phospholipid (PL) fatty acids and biochemical parameters were detected by standard methods. Plasma PL C22:6n-3 was significantly lower in case group than in control group, and was negatively correlated with fasting glucose (r = −0.177, p < 0.001). Higher plasma PL C22:6n-3 was associated with lower risk of T2DM, and the OR was 0.32 (95% confidence interval (CI), 0.12 to 0.80; p = 0.016) for per unit increase of C22:6n-3. UA was significantly lower in case group than in control group. UA was positively correlated with fasting glucose in healthy subjects, but this correlation became negative in T2DM subjects. A significant interaction was observed between C22:6n-3 and UA on fasting glucose (p for interaction = 0.005): the lowering effect of C22:6n-3 was only significant in subjects with a lower level of UA. In conclusion, C22:6n-3 interacts with UA to modulate glucose metabolism.

Prevalence and clinical predictors of insulin resistance in reproductive-aged thai women with polycystic ovary syndrome

Objectives. To determine the prevalence of insulin resistance (IR) and its predictors in reproductive-aged Thai women with polycystic ovary syndrome (PCOS). Methods. A cross-sectional study was conducted from May 2007 to January 2009. Participants were 250 Thai women with PCOS. Information regarding medical history and physical examination and results of 75 gram OGTT were recorded. Results. The overall prevalence of IR was 20.0%, comprising the prevalence of impaired fasting glucose, impaired glucose tolerance, and diabetic mellitus of 3.2%, 13.6%, and 5.6%, respectively. Multiple logistic regression analysis showed that the independent predictors for IR were age of ≥30 years old, waist circumference (WC) of ≥80 cm, presence of acanthosis nigricans (AN), and dyslipidemia with odds ratios (95% confidence interval) of 2.14 (1.01-4.52), 3.53 (1.28-9.75), 2.63 (1.17-5.88), and 3.07 (1.16-8.11), respectively. Conclusion. The overall prevalence of IR in reproductive-aged Thai women with PCOS is 20.0%. Age ≥30 years old, WC ≥80 cm, the presence of AN, and dyslipidemia are the significant clinical predictors.

Selected compounds derived from Moutan Cortex stimulated glucose uptake and glycogen synthesis via AMPK activation in human HepG2 cells

AIM OF THE STUDY

To evaluate the effect of selected compounds derived from Moutan Cortex on glucose uptake and glycogen synthesis associated with AMPK activation in insulin-resistant human HepG2 cell.

MATERIALS AND METHODS

The effect of isolated compounds (1-16) on glucose uptake and glycogen synthesis was performed using HepG2 cells. The western blot was used to determine the expression of AMPK and its downstream substrates, ACC, p-ACC, and p-GSK-3beta.

RESULTS

The effects of the 16 compounds from Moutan Cortex on glucose metabolism in HepG2 cells under high glucose conditions were evaluated. Compounds 2, 3, and 6 displayed highly potent effects on the stimulation of glucose uptake and glycogen synthesis in human HepG2 cells under high glucose conditions. Compounds 2, 3, and 6 phosphorylate AMPK (AMP-activated protein kinase), and resulted in increased phosphorylation of GSK-3beta and suppression of lipogenic expression (ACC and FAS) in a dose-dependent manner. Compounds 2, 3, and 6 also demonstrated interesting, strong eNOS phosphorylation in human umbilical vein endothelial cells (HUVECs). Compounds 1, 4, 5-12, and 14 displayed considerable effects on hepatic glucose production, AMPK activation, and phosphorylation of GSK-3beta in HepG2 cells under high glucose conditions.

CONCLUSIONS

These effects may indicate that the activation of AMPK by the active compounds from Moutan Cortex has considerable potential for reversing the metabolic abnormalities associated with type-2 diabetes.

Metabolic syndrome is more associated with intracranial atherosclerosis than extracranial atherosclerosis

To elucidate the relationship between metabolic syndrome (MetS) and cerebrovascular stenosis, we performed comparative studies of MetS and its components between ischemic stroke patients with intra- and extracranial atherostenosis. We evaluated 378 acute ischemic stroke patients who underwent brain magnetic resonance (MR) imaging and MR angiography. Stenosis was diagnosed in cases showing a degree of luminal narrowing of > or = 50%. The stroke subtypes were categorized as large artery atherosclerosis (LAA), small artery occlusion (SAO), cardioembolism (CE), and stroke of undetermined etiology (SUE). MetS was defined using the criteria of the Adult Treatment Panel III. The mean carotid intimal medial thickness values showed increased tendency as the number of MetS components increased (P < 0.001). Regardless of stroke subtype, the MetS (+) group showed an increasing tendency toward stenosis (LAA, SAO, all P < 0.001; CE, P = 0.001; SUE, P = 0.077). MetS was independently associated with intracranial atherosclerosis (odds ratio, 3.58; 95% CI, 2.28-5.63), which was prominent with more severe MetS components after adjustment for other risk factors (P < 0.001). Amongst the component conditions, elevated blood pressure, increased blood glucose/hyperglycemia, and abdominal obesity were dominantly associated with stenosis (all P < 0.001). Modifications of the individual MetS components need to be considered for stroke prevention because of intracranial atherogenic progression.

Impaired renal function and atherosclerosis in a Pakistani cohort

OBJECTIVE

To investigate the relationship of creatinine and calculated glomerular filtration rate (GFR) with coronary arterial disease (CAD) in Pakistani patients.

SUBJECTS

Four hundred individuals with chest pain; 200 with angiographic disease matched with 200 without occlusive disease.

DESIGN

A prospective case-control study.

SETTING

A tertiary referral cardiology unit in Pakistan.

RESULTS

Impaired renal function as estimated by calculated GFR was common in this population. Creatinine and glomerular filtration rate, as calculated by the Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) formulae, were associated with CAD and atherosclerotic burden in Pakistani patients. Calculation of creatinine clearance, correcting for age, sex and body mass index, showed that clearance was 81 (17-257) mL/min/1.73 m2 in patients with CAD compared with 88 (23-167) mL/min/1.73 m2 in controls with a significant number of patients (18.5 vs. 6.5%; RR = 2.85; p < 0.001) showing significant renal impairment (< 60 mL/min/1.73 m2) by CG and more by the MDRD equation (26 vs. 9%; RR = 2.88; p < 0.001). The unadjusted odds ratios for CAD for a GFR < 60 mL/min/1.73 m2 were 3.66 (1.87-7.16) and 3.29 (1.81-6.01), respectively and, after adjustment for diabetes, smoking, insulin resistance, inflammation and apolipoprotein A1, 1.04 (1.02-1.09) and 1.04 (1.02-1.09), respectively.

CONCLUSIONS

Impaired renal function is common in Pakistani patients with coronary arterial disease and is strongly associated with a risk of atherosclerosis independent of insulin resistance.

Mechanisms, Significance and Treatment of Vascular Dysfunction in Type 2 Diabetes Mellitus

Endothelial dysfunction and increased arterial stiffness occur early in the pathogenesis of diabetic vasculopathy. They are both powerful independent predictors of cardiovascular risk. Advances in non-invasive methodologies have led to widespread clinical investigation of these abnormalities in diabetes mellitus, generating a wealth of new knowledge concerning the mechanisms of vascular dysfunction, risk factor associations and potential treatment targets. Endothelial dysfunction primarily reflects decreased availability of nitric oxide (NO), a critical endothelium-derived vasoactive factor with vasodilatory and anti-atherosclerotic properties. Techniques for assessing endothelial dysfunction include ultrasonographic measurement of flow-mediated vasodilatation of the brachial artery and plethysmography measurement of forearm blood flow responses to vasoactive agents. Arterial stiffness may be assessed using pulse wave analysis to generate measures of pulse wave velocity, arterial compliance and wave reflection. The pathogenesis of endothelial dysfunction in type 2 diabetes is multifactorial, with principal contributors being oxidative stress, dyslipidaemia and hyperglycaemia. Elevated blood glucose levels drive production of reactive oxidant species (ROS) via multiple pathways, resulting in uncoupling of mitochondrial oxidative phosphorylation and endothelial NO synthase (eNOS) activity, reducing NO availability and generating further ROS. Hyperglycaemia also contributes to accelerated arterial stiffening by increasing formation of advanced glycation end-products (AGEs), which alter vessel wall structure and function. Diabetic dyslipidaemia is characterised by accumulation of triglyceride-rich lipoproteins, small dense low-density lipoprotein (LDL) particles, reduced high-density lipoprotein (HDL)-cholesterol and increased postprandial free fatty acid flux. These lipid abnormalities contribute to increasing oxidative stress and may directly inhibit eNOS activity. Although lipid-regulating agents such as HMG-CoA reductase inhibitors (statins), fibric acid derivatives (fibrates) and fish oils are used to treat diabetic dyslipidaemia, their impact on vascular function is less clear. Studies in type 2 diabetes have yielded inconsistent results, but this may reflect sampling variation and the potential over-riding influence of oxidative stress, dysglycaemia and insulin resistance on endothelial dysfunction. Results of positive intervention trials suggest that improvement in vascular function is mediated by both lipid and non-lipid mechanisms, including anti-inflammatory, anti-oxidative and direct effects on the arterial wall. Other treatments, such as renin-angiotensin-aldosterone system antagonists, insulin sensitisers and lifestyle-based interventions, have shown beneficial effects on vascular function in type 2 diabetes. Novel approaches, targeting eNOS and AGEs, are under development, as are new lipid-regulating therapies that more effectively lower LDL-cholesterol and raise HDL-cholesterol. Combination therapy may potentially increase therapeutic efficacy and permit use of lower doses, thereby reducing the risk of adverse drug effects and interactions. Concomitant treatments that specifically target oxidative stress may also improve endothelial dysfunction in diabetes. Vascular function studies can be used to explore the therapeutic potential and mechanisms of action of new and established interventions, and provide useful surrogate measures for cardiovascular endpoints in clinical trials.

Insulin-lowering agents in the management of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a medical condition that has brought multiple specialists together. Gynecologists, endocrinologists, cardiologists, pediatricians, and dermatologists are all concerned with PCOS patients and share research data and design clinical trials to learn more about the syndrome. Insulin resistance is a common feature of PCOS and is more marked in obese women, suggesting that PCOS and obesity have a synergistic effect on the magnitude of the insulin disorder. Hyperinsulinemia associated with insulin resistance has been causally linked to all features of the syndrome, such as hyperandrogenism, reproductive disorders, acne, hirsutism, and metabolic disturbances. Women with PCOS should be evaluated for cardiovascular risk factors, such as lipid profile and blood pressure. Modification of diet and lifestyle should be suggested to those who are obese. Several insulin-lowering agents have been tested in the management of PCOS. In particular, metformin is the only drug currently in widespread clinical use for treatment of PCOS. In a high percentage of patients, treatment with metformin is followed by regularization of menstrual cycle, reduction in hyperandrogenism and in cardiovascular risk factors, and improvement in response to therapies for induction of ovulation.

Antihypertensive, antiatherosclerotic and antioxidant activity of triterpenoids isolated from Olea europaea, subspecies africana leaves

For the first time a biossay-directed study of triterpenoids isolated from the leaves of Olea europaea from Greece, from wild African olive and from a cultivar of O. europaea grown in Cape Town was reported. The experiment was undertaken since our preliminary analyses showed that the African wild olive leave is rich in triterpenoids and contain only traces of the glycoside oleuropein, which is typical for the European olive leaves. The isolate of the African wild olive leaves (AO) used in the experiments was found to contain 0.27% 1:1 mixture of oleanolic acid and ursolic acid, named oleuafricein. The isolate of Greek olive leaves (GO) was found to contain 0.71% oleanolic acid, and the Cape Town cultivar (CT) contained 2.47% oleanolic acid. No ursolic acid was found in either GO or CT. The antihypertensive, diuretic, antiatherosclerotic, antioxidant and hypoglycemic effects of authentic oleanolic and ursolic acid and the three isolates (GO, AO and CT) were studied on Dahl salt-sensitive (DSS), insulin-resistant rat genetic model of hypertension. All three isolates, in a dose 60 mg/kg b.w. for 6 weeks treatment, prevented the development of severe hypertension and atherosclerosis and improved the insulin resistance of the experimental animals. GO, OA and CT isolates could provide an effective and cheap treatment of this particular, most common type of salt-sensitive hypertension in the African population.

Postoperative management of the diabetic patient

Diabetic patients are at increased risk for adverse outcomes of surgery. These adverse outcomes are related to pre-existing complications of diabetes, especially atherosclerotic disease, nephropathy (and perhaps increased susceptibility to other renal toxins), and peripheral and autonomic neuropathy. Hyperglycemia is associated with likely risks for poorer wound healing, increased susceptibility to infection, and probable loss of administered nutrients through glycosuria. Insulin use has the flexibility of timing and dose in the postoperative management of most diabetic patients. The combinations of intermediate-acting and long-acting insulins and short-acting insulins usually are related to the experience and preferences of the treating physicians and allied health professionals. Intravenous insulin (always R) may be limited to administration in the ICU because of the need for frequent blood glucose monitoring and rapidity of glucose response to intravenous insulin. The use of short-acting insulin analogues has been shown to work well as premeal insulin or for rapidly treating marked hyperglycemia in the outpatient setting. Meal delivery in the hospitalized patient may not be timed as precisely as in the home situation. Nurses may be responsible for many patients. The rapid-acting analogues may be associated with increased risk for hypoglycemia in the hospitalized patient if insulin cannot be given immediately before a meal. These rapid-acting insulin analogues usually are limited to circumstances in which the patient can determine the dose and self-administer just before ingestion of the meal. The long-acting insulin analogues may not afford enough flexibility in many situations in which daily dosages changes are occurring in intermediate-acting and long-acting insulins. Oral glucose-lowering agent use in the postoperative state usually is limited to selected patients, including patients who have been on such agents before surgery, who have only mild elevations of blood glucose, who are able to ingest oral medications, and who do not have significant comorbid conditions (or significant risk for such conditions) that may be contraindications to use of such agents (see Table 3). Sulfonylureas and other insulin secretagogues (e.g., meglitinide, nateglinide) lower glucoses acutely. The risk for hypoglycemia is slightly less with the nonsulfonylurea agents. Efficacy and side effects limit the use of carbohydrase inhibitors for hospitalized patients. The glucose-lowering effects of biguanides and thiazolidinediones usually are not rapid enough for hospitalized patients who have never taken these medications. For patients who have been on a biguanide or thiazolidinedione before admission, these agents often are restarted in the postoperative period when oral intake of medications is possible and hepatic and renal function are stable. The hospital period affords an opportunity to review long-term management issues related to diabetes and its complications. Instruction on the importance of medical nutrition therapy, glycemic control, management of hypertension, dyslipidemia, and aspirin use as well as basic guidelines for foot care should be carried out during the hospitalization and at the time of discharge. Similarly, appropriate arrangements for medical nutrition therapy, general diabetes education (especially for newly diagnosed diabetic patients), and regular medical follow-up are important to ensure long-term, excellent surgical and medical outcomes.

The long term health consequences of polycystic ovary syndrome

Women with polycystic ovary syndrome have both insulin resistance and beta cell dysfunction. Consequently, they are at increased risk of developing diabetes and cardiovascular disease. Women with polycystic ovary syndrome present to clinicians at a young age and as such offer a unique opportunity to identify insulin resistant patients at an early stage. This enables the modification of risk factors and diagnosis of diabetes before the onset of macro- and micro-vascular symptoms. Increased emphasis should thus be placed on long term risk management and diabetic screening with advice on smoking, exercise and, if appropriate, weight loss. Where possible drugs that exacerbate insulin resistance should be avoided and consideration should be given to the use of insulin sensitising agents, particularly in the obese.

Effects of comicronised fenofibrate on lipid and insulin sensitivity in patients with polymetabolic syndrome X

BACKGROUND

This study investigated the effects of comicronised fenofibrate in patients with dyslipidemia and polymetabolic syndrome X.

DESIGN

After a 6-week dietary run-in phase, 37 male patients eligible on lipid criteria entered a 12-week treatment phase consisting of diet plus one capsule daily containing 200 mg of comicronised fenofibrate (Lipanthyl(R)).

RESULTS

A significant reduction in plasma concentrations of total cholesterol, LDL cholesterol and triglyceride was observed after 4, 8 and 12 weeks of treatment with fenofibrate. The improvement in the atherogenic index LDL/HDL cholesterol from a pretreatment 3.8 to 3.0 after treatment was highly statistically significant and may be judged as satisfactory. Significant changes were also observed in haemostatic factors (fibrinogen reduced by 19%, factor VII activity reduced by 18%). Fasting serum insulin levels and insulin response (area under the curve) after oral glucose load were significantly reduced by 26.8% and 18.7%, respectively, indicating an improvement of insulin sensitivity. Systolic and diastolic blood pressure were significantly reduced. Uric acid was significantly reduced by 21.6%.

CONCLUSION

These favourable effects of comicronised fenofibrate both on lipid and non lipid parameters, including insulin sensitivity, may confer to this product a particular interest in the treatment of patients with polymetabolic syndrome X.

Current concepts in preeclampsia

The purpose of this article is to review recent epidemiologic and pathophysiologic findings that advance the understanding of preeclampsia for the nurse in perinatal practice. Preeclampsia is different from other hypertensive disorders of pregnancy. Risk factors for preeclampsia and recent findings regarding normal and aberrant implantation are presented. Abnormal implantation and resulting poor placental perfusion may be the impetus for endothelial changes evidenced in preeclampsia; pathophysiology is described in relation to this event. The interaction of maternal factors, reduced placental perfusion, and endothelial cell dysfunction provides an explanation for the occurrence of preeclampsia and provides a basis for nursing practice and research. Implications for nursing care for women of childbearing age before, during, or after pregnancy may include (a) preconception or post-delivery counseling to reduce modifiable risk factors such as obesity, sedentary lifestyle, or high fat intake, (b) assessment of risk factors and increased surveillance when risk factors are present, and (c) surveillance of blood pressure changes of > 30 mmHg systolic or > 15 mmHg diastolic in advance of the third trimester of pregnancy.

Cellular mechanism of nutritionally induced insulin resistance: the desert rodent Psammomys obesus and other animals in which insulin resistance leads to detrimental outcome

Animal species with genetic or nutritionally induced insulin resistance, diabetes and obesity (diabesity) may be divided into two broad groups: those with resilient pancreatic beta-cells, e.g. ob/ob mice and fa/fa rats, capable of long-lasting compensatory insulin over-secretion, and those with labile beta-cells in which the secretion pressure leads to irreversible beta-cell degranulation, e.g. db/db mice, Macaca mulatta primates, ZDF diabetic rats. Prominent in this group is the Israeli desert gerbil Psammomys obesus (sand rat), which features low insulin receptor density in liver and muscle. On a diet of relatively high energy, the capacity of insulin to activate the receptor tyrosine kinase (TK) is reduced, in the face of hyperinsulinemia. With the following hyperglycemia, the rising insulin resistance imposes a vicious cycle of insulinemia and glycemia, accentuating the TK activation failure and the beta-cell failure. Among various factors affecting the insulin signaling pathway, multisite phosphorylation, including serine and threonine on the receptor beta-subunit, due to overexpression of certain protein kinase C isoforms, seems to be responsible for the inhibition of the critical step of TK phosphorylation activity. The compromised TK activation is reversible by diet restriction which restores to normal the glycemia and insulinemia. The beta-cell response to long-lasting stimulation and the receptor malfunction in diabesity have implications for a similar etiology in human insulin resistance syndrome and type 2 diabetes, particularly in populations emerging from a food scarce environment into nutritional affluence, inappropriate to the human metabolic capacity. It is suggested that the "thrifty gene" is characterized by a low threshold for insulin secretion and low capacity for insulin clearance. Thus, nutritionally-induced hyperinsulinemia is potentiated and becomes the primary phenotypic expression of the thrifty gene, linked to the insulin receptor signaling pathway malfunction.

Regional body composition determined by dual-energy X-ray absorptiometry. Relation to training, sex hormones, and serum lipids in male long-distance runners

This study investigated the regional distribution of fatty and lean tissue in long-distance runners, and the relation to training, sex hormones, and serum lipids. One hundred and twenty lean men (22 elite, 86 recreational runners and 12 non-running controls) aged 32 +/- 8.1 years (mean +/- SD) participated. Body composition (adipose and lean tissue) was measured by dual-energy x-ray absorptiometry in the total body and in the abdomen, the arms and the legs. Regional and total body fat correlated inversely with the performance at an incremental treadmill exercise test (-0.61 < r < -0.52, P < 0.0001), and the fat percentage in the abdomen and in the legs was 42% and 36% lower in the elite runners in comparison with the non-running controls. Sex hormonal status and serum lipids were unrelated to training. After multiple regression analysis the most significant determinant of the fat percentage in the legs was the weekly distance run (partial r = -0.40, P < 0.0001), whereas in the abdominal region the free testosterone index also contributed strongly (partial r = 0.39, P < 0.0001). In conclusion, long-distance runners had very low amounts of fatty tissue in the abdomen and in the extremities, and the fat percentages in the abdomen and in the legs were associated with both the training intensity and androgenic activity. Since the abdominal fatty tissue is a significant risk factor for cardiovascular disease, running may have a positive impact on the long-term risk.

Diabetes and Atherosclerosis: Mechanisms and Management

OBJECTIVE

To discuss the association of diabetes and atherosclerosis and outline various management options.

METHODS

We reviewed the findings in pertinent studies in the literature.

RESULTS

Atherosclerosis accounts for virtually 80% of all diabetes-related mortality. It is also a principal reason for hospitalization of patients with diabetes. Diabetes profoundly affects the pathogenesis of atherosclerosis through various mechanisms. Established cardiovascular risk factors are more prevalent in diabetic than in nondiabetic patients. Although trials of intensive glycemic control have been somewhat disappointing for decreasing atherogenesis, the results of trials with lipid-regulating therapies have been more encouraging.

CONCLUSION

Atherogenesis is a multifactorial, multi-stepped process. Although established risk factors do not entirely explain the increased risk of cardiovascular disease in patients with diabetes, they do seem to have a major role. Therefore, the management of patients with diabetes must address these contributing risk factors.

Apo E isoforms, insulin output and plasma lipid levels in essential hypertension

BACKGROUND

The association between apo E isoforms and insulin output during the oral glucose test (OGTT) in 60 non-diabetic, non-obese patients with essential hypertension and in control subjects (non-obese, non-diabetic normotensive subjects) was estimated.

METHODS

According to low or high insulin output during OGTT, the subjects were divided into the following groups: normotensive subjects with low (NLI) and high (NHI) and hypertensive subjects with low (HLI) and high (HHI) insulin output.

RESULTS

The apo E 4/2 phenotype was detected in 32% of hypertensive subjects but not in control subjects. The frequency of apo E 3/2 phenotype in hypertensive subjects was 5% and in normotensive subjects 15%. An increased frequency of phenotype apo E 4/3 was noticed both in HHI (46%) and in NHI (50%) compared with HLI (22%) and NLI (17%) groups.

CONCLUSION

The results suggest that the determination of phenotypes apo E and insulin output may contribute to an early detection of individuals at high risk of hypertension development.

Moderately obese, insulin-resistant women exhibit abnormal vascular reactivity to stress

To define the hemodynamic implications of insulin resistance (IR), we compared 10 normotensive, insulin-resistant women who had abnormal glucose tolerance tests with 10 age-matched healthy normotensive women with normal glucose tolerance tests with respect to mental arithmetic and handgrip responses. Hemodynamic variables obtained at baseline and during stress included heart rate, blood pressure, cardiac output, and systemic vascular resistance. The IR group weighed more (84 versus 66 kg). Screening BP was similar (123/72 versus 120/68 mm Hg, P=NS) between groups although baseline diastolic BP at testing day was higher in the IR group than control group (75 versus 65 mm Hg, P<.05). The IR group showed a significantly greater increase in systolic (18% versus 10%, P<.O1) and diastolic (24% versus 12%, P<.01) blood pressure responses to mental stress than the control group. During mental stress, the control group demonstrated increased cardiac output (1.4 L/min) and decreased systemic vascular resistance (-120 dyne x s x cm[-5]), whereas IR subjects demonstrated increased systemic vascular resistance (119 dyne x s x cm(-5); group difference, P<.02) with only a small increase in cardiac output (0.5 L/min). Handgrip also caused a greater increase in systemic vascular resistance in the IR group (252 versus 64 dyne x s x cm(-5), P<.05), with a correspondingly greater increase in blood pressure than control subjects. Baseline blood pressure was correlated with weight (r=.41, P<.02) and stress blood pressure with fasting insulin (r=.51, P<.001) and glucose-to-insulin ratio (r= -.55, P<.001). We conclude that insulin resistance is associated with an exaggerated blood pressure response to stress; an enhanced vasoconstriction to stress may mediate this response. This hyperreactivity may be a marker for future hypertension in obese, normotensive, hyperinsulinemic individuals.

Maternal and fetal modulators of lipid metabolism correlate with the development of preeclampsia

The pregnancy syndrome preeclampsia is associated with placental dysfunction, dyslipidemia, and endothelial cell activation, and is a major cause of maternal and fetal morbidity and mortality. In this report, a nested case-control study of matched preeclamptic and normal pregnant women was used to investigate the association of maternal and fetal modulators of lipid metabolism with pregnancy outcome. Maternal body mass index (BMI), triglyceride levels, and nonesterified fatty acid (NEFA) concentrations were all significantly increased in women who developed preeclampsia (P < .01). Human placental lactogen (hPL), which is secreted by the syncytiotrophoblast layer of the fetal placenta and reportedly has lipolytic activity, also was found to be elevated in women with preeclampsia (P < .01). By contrast, hemoglobin levels were not found to be statistically different between the two groups of women, indicating that the increased plasma lipids and hPL were not a result of hemoconcentration in preeclamptic patients. The results suggest a multihit hypothesis for the pathophysiology of preeclampsia in which maternal obesity and a placental lipolytic hormone (hPL) converge to adversely affect free fatty acid concentrations in the maternal circulation.

Intracellular free calcium abnormalities in fibroblasts from non-insulin-dependent diabetic patients with and without arterial hypertension

As arterial hypertension is frequently associated with diabetes, it is possible that altered intracellular free calcium ([Ca2+]i) handling, as reported in non-insulin-dependent diabetic patients, is accounted for by abnormalities caused by hypertension rather than diabetes. Our aim was to investigate [Ca2+]i transients triggered by two extracellular agonists, bradykinin and angiotensin II, with or without chronic insulin exposure, in cultured skin fibroblasts from 10 normotensive and 10 hypertensive non-insulin-dependent patients, matched for age, body mass index, and metabolic control, with fibroblasts from 10 healthy control subjects. Long-term cultured fibroblasts were loaded with fura 2-AM for measurement of [Ca2+]i. Resting [Ca2+]i levels were similar in the three groups of subjects. [Ca2+]i spikes stimulated by angiotensin II (0.1 mumol/L) and bradykinin (1 mumol/L) were significantly greater in hypertensive non-insulin-dependent diabetic patients (216 +/- 43 and 374 +/- 39 nmol/L, respectively) than in normotensive patients (174 +/- 16 and 267 +/- 55 nmol/L) and control subjects (188 +/- 29 and 320 +/- 78 nmol/L). Also, ionomycin evoked a greater [Ca2+]i response in hypertensive than normotensive non-insulin-dependent diabetic patients and in control subjects. Chronic insulin exposure increased by 70% to 90% the [Ca2+]i response to both angiotensin II and bradykinin in control subjects and normotensive non-insulin-dependent diabetic patients but not in hypertensive patients. The presence of abnormalities in [Ca2+]i transients in fibroblasts from only hypertensive non-insulin-dependent diabetic patients supports the possibility that these defects are a feature of concomitant arterial hypertension rather than of diabetes or its disturbed metabolic milieu.

Gender considerations in hypertension pathophysiology and treatment

Cardiovascular disease is the leading cause of death among women, yet clinical trials have not evaluated specific treatment strategies for women. Recently, there has been an expansion of scientific literature exploring differences between women and men with hypertension and cardiovascular disease. The cardioprotective effects of estrogen have been well demonstrated, and the loss of endogenous estrogens with aging contributes to the rapid increase in the incidence of coronary artery disease after menopause. Many of the adverse effects of estrogen deficiency are reversible with estrogen replacement. Estrogen improves lipoprotein profiles, has vasodilatory effects on the endothelium, and inhibits vascular smooth muscle cell growth and constriction. These effects likely all contribute to the reduction in coronary artery disease in the presence of estrogen, and the clinical benefits are not attenuated by concurrent progestins. There are gender-specific differences in the epidemiology of hypertension and coronary artery disease, as well as differences in the pathophysiology and clinical manifestations of disease. Given important experimental interactions between estrogens and the major classes of antihypertensive agents, as well as secondary benefits such as a possible reduction in bone loss with certain agents, a gender-specific approach to hypertension appears to be warranted. Future clinical trials will need to address gender-specific differences in treatment approaches.

Insulin is required for angiotensin II-mediated hypertrophy of smooth muscle cells

The prevalence of hypertension and atherosclerosis among subjects with hyperinsulinemia supports the premise of a direct metabolic link between insulin and angiotensin II at the cellular level. In the present study, the effect of insulin on the angiotensin II-induced growth of A10 smooth muscle cells (SMC) was investigated. Treatment of quiescent A10 cells with angiotensin II caused an increase in RNA synthesis, proto-oncogene c-fos mRNA levels and cell size dependent upon pretreatment with insulin. The insulin requirement was independent of its actions as a growth factor, since a pre-treatment of at least 24 h with insulin was essential for growth stimulation by angiotensin II. Using RT-PCR, insulin was shown to regulate AT2 receptor expression in both quiescent and differentiating cells. These data suggest the AT2 receptor, which mediates the growth effects of angiotensin II in A10 cells, may be the critical target for the effect of insulin.

Influence of a diet regimen on glucose homeostasis and serum lipid levels of male elite athletes

Physical training affects carbohydrate metabolism and results in an increased insulin-stimulated glucose disposal. To investigate if carbohydrate and lipid metabolism would be affected by nutritional factors in optimally trained elite athletes, during a 1-year period we studies elite ice-hockey players on two Swedish top-performance teams. Players on one team were subjected to extensive dietary monitoring and intervention, whereas players on the second team continued their ordinary diet. Blood levels of insulin, C-peptide, glucose, hemoglobin A1C (HbA1c), lipids, and lipoproteins were measured repeatedly. Basal insulin levels and insulin resistance (IR) were significantly lower among athletes on both teams compared with a sedentary group, and muscle weight and body mass index were significantly higher. During the course of the study in the intervention group, insulin levels decreased (3.6 +/- 0.3 v 6.2 +/- 0.6 [mean +/- SEM], P <.05) in conjunction with a decreased relative fat energy content, but returned toward baseline levels when relative fat energy content increased. IR decreased in parallel (0.59 +/- 0.05 v l.12 +/- 0.12, P <.05) and followed a similar pattern, reverting toward baseline levels. Also, levels of HbA1c changed during dietary manipulation. No changes in these parameters were observed among the elite players from the team not participating in the diet regimen. In contrast to the parameters for glucose homeostasis, no significant changes were found in serum lipid or lipoprotein levels in either team during the course of the study. The results verify the presence of an improved carbohydrate metabolism in elite athletes. The observed changes in glycemic control and glucose homeostasis as a consequence of dietary modification demonstrate further that nutritional factors may affect carbohydrate metabolism also in well-trained athletes.

Insulin resistance is mediated by a proteolytic fragment of the insulin receptor

Insulin resistance is a common clinical feature of obesity and non-insulin-dependent diabetes mellitus, and is characterized by elevated serum levels of glucose, insulin, and lipids. The mechanism by which insulin resistance is acquired is unknown. We have previously demonstrated that upon chronic treatment of fibroblasts with insulin, conditions that mimic the hyperinsulinemia associated with insulin resistance, the membrane-associated insulin receptor beta subunit is proteolytically cleaved, resulting in the generation of a cytosolic fragment of the beta subunit, beta', and that the generation of beta' is inhibited by the thiol protease inhibitor E64 (Knutson, V. P. (1991) J. Biol. Chem. 266, 15656-15662). In this report, we demonstrate that in 3T3-L1 adipocytes: 1) cytosolic beta' is generated by chronic insulin administration to the cells, and that E64 inhibits the production of beta'; 2) chronic administration of insulin to the adipocytes leads to an insulin-resistant state, as measured by lipogenesis and glycogen synthesis, and E64 totally prevents the generation of this insulin-induced cellular insulin resistance; 3) E64 has no effect on the insulin-induced down-regulation of insulin receptor substrate-1, and therefore insulin resistance is not mediated by the down-regulation of insulin receptor substrate-1; 4) under in vitro conditions, partially purified beta' stoichiometrically inhibits the insulin-induced autophosphorylation of the insulin receptor beta subunit; and 5) administration of E64 to obese Zucker fatty rats improves the insulin resistance of the rats compared to saline-treated animals. These data indicate that beta' is a mediator of insulin resistance, and the mechanism of action of beta' is the inhibition of the insulin-induced autophosphorylation of the beta subunit of the insulin receptor.

Effects of pioglitazone on calcium channels in vascular smooth muscle

Pioglitazone, an insulin-sensitizing, antidiabetic agent, has blood pressure-lowering effects in insulin-resistant hypertensive rats and attenuates growth factor-induced increases of intracellular Ca2+ in rat aortic vascular smooth muscle cells. To determine whether modulation of voltage-dependent Ca2+ channels plays a role in this association, we investigated the effects of pioglitazone on voltage-dependent current in cultured rat aortic (a7r5) and freshly dissociated rat tail artery vascular smooth muscle cells. Both cell types were studied with whole-cell patch-clamp techniques. Current through L-type Ca2+ channels was elicited with a voltage ramp in the presence of Ba2+ substituted for Ca2+. T-type Ca2+ current was studied using a two-pulse protocol that enabled the isolation of transient current. In a7r5 vascular smooth muscle cells, 2-minute application of pioglitazone (5 and 10 mumol/L) reduced L-type current by 7.9 +/- 1.0% (n = 8) (mean +/- SEM, number of cells) and 14.5 +/- 3.0% (n = 9) (P < .01, two-tailed paired t test), respectively. In contrast, 2-minute application of pioglitazone had no significant effect on T-type Ca2+ current. In freshly dissociated tail artery vascular smooth muscle cells, 2-minute application of 10 mumol/L pioglitazone had an insignificant effect (4.8 +/- 5.6% reduction); however, 25 mumol/L pioglitazone reduced L-type current by 27.3 +/- 7.2% (n = 5) (P < .01). Two-minute application of 0.1% or 0.2% dimethyl sulfoxide (vehicle) alone had no significant effects on currents in either type of vascular smooth muscle cell.(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes mellitus: a disease of abnormal cellular calcium metabolism?

Although the pathogenesis of the diabetes mellitus syndrome remains poorly understood, both insulin-dependent diabetes mellitus and non-insulin-dependent diabetes mellitus predispose the individual to a similar spectrum of complications, including hypertension, macrovascular and microvascular disease, cataracts cardiomyopathy, neuropathy, and premature aging, suggesting that these complications develop along a pathway common to both diabetic conditions. Yet not all diabetic persons are affected by all of these complications or to the same degree. What causes this marked variability in the clinical manifestations of the diabetes syndrome remains an enigma. Accumulating data from animal models of diabetes and from studying patients with diabetes reveal that intracellular calcium levels are increased in most tissues. The activities of the membrane, adenosine triphosphatase (ATPase) associated cation pumps, which determine intracellular calcium level (i.e., calcium-ATPase and [sodium + potassium]-ATPase), are also altered. The nature of the alteration is often tissue specific and may depend on the level of blood glucose or insulin, or both. In this review we discuss the potential contribution of these changes in intracellular calcium regulation, whether acquired or genetically determined, to the pathogenesis of the diabetes syndrome, to the abnormalities in insulin secretion and action (mainly in non-insulin-dependent diabetes), and to the complications of both diabetes syndromes. Altered intracellular calcium metabolism may represent a common, underlying abnormality linking the metabolic, cardiovascular, ocular, and neural manifestations of the diabetic disease process.

Insulin resistance in hypertension: a focused review

The associations between insulin resistance, hyperinsulinemia, and hypertension are well recognized. The insulin resistance and hyperinsulinemia associated with hypertension is the result of increased renal tubular sodium reabsorption, increased sympathetic nervous system activity, and increased arterial wall smooth muscle reactivity. In insulin resistant states, intracellular calcium and sodium accumulation is thought to be the fundamental underlying abnormality. These is evidence that hyperinsulinemia is an independent risk factor for coronary artery disease. Therefore, therapeutic considerations in patients with insulin resistance should include nonpharmacologic methods for increasing insulin sensitivity as well as avoiding the deleterious effects on insulin action and lipid metabolism of various antihypertensive medications. Of the currently available antihypertensives therapies, the angiotensin-converting enzyme inhibitors, the alpha antagonists, and the calcium channel blockers are the most rational choices for treating patients with hypertension with evidence of coexisting insulin resistance.

Effects of pyrazinoylguanidine on the glucose-fatty acid cycle in normal subjects and patients with non-insulin-dependent diabetes mellitus

Pyrazinoylguanidine (PZG) reduced the hyperglycemia, hyperinsulinemia, and hyperlipidemia of patients with non-insulin-dependent diabetes mellitus (NIDDM) as well as of normal subjects receiving hydrochlorothiazide (HCTZ). Mechanisms are proposed by which PZG downregulated the elevated glucose-fatty acid cycle toward a more normal level in NIDDM patients and in non-diabetic subjects maintained on HCTZ. Despite maintenance of these NIDDM patients on their current antihypertensive medication, PZG reduced further their systolic and diastolic pressures. PZG was well tolerated by both normal and NIDDM patients.

Sex-specific effects of an insulin secretagogue in stroke-prone hypertensive rats

Glyburide, an insulin secretagogue and an insulin-sensitizing agent, lowers blood pressure in normal male and female dogs when administered acutely. Because insulin resistance may contribute to spontaneous hypertension in rats, we sought to determine if long-term administration of glyburide (5 mg/kg per day by diet, age 5 weeks to 5 months) would lower blood pressure in male and female stroke-prone spontaneously hypertensive rats. Arterial (aortic) rings from these rats were incubated with insulin in vitro (100 mU/mL) 1 hour before and during phenylephrine-induced contraction to determine if long-term glyburide administration improves vascular sensitivity to the intrinsic vasodilator action of insulin. Glyburide, however, significantly increased blood pressures and ratios of heart weight to body weight in 5-month-old female rats (+20 mm Hg diastolic, P < .05), with no significant change noted in male rats (+4 mm Hg diastolic). Glyburide increased plasma insulin levels (twofold, P < .04) in female but not in male rats. Glyburide did not affect plasma glucose or catecholamine levels. After incubation with insulin, aortic to rings from glyburide-treated female rats demonstrated more than 40% greater contractile responsiveness the phenylephrine compared with aortic rings from control female rats (P < .04). This insulin-dependent increase in phenylephrine-induced contraction consisted of a reversal in the in vitro action of insulin, from attenuation to accentuation of such contraction (P < .05). This change was not seen in male rats. Neither gender, glyburide, nor insulin influenced acetylcholine-induced relaxation of phenylephrine-induced contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular insulin abnormalities, hypertension, and accelerated atherosclerosis

There is accumulating evidence that insulin resistance, glucose intolerance, and hyperinsulinemia exist in people with high blood pressure, and it has been suggested that insulin resistance and hyperinsulinemia may be of great importance in the origin of hypertension and its ultimate clinical course. Of importance are the recent observations that persons with normal glucose tolerance, selected on the basis of hyperinsulinemia, had higher blood pressure than matched individuals with normoinsulinemia. Hypertension in in insulin-resistant states generally has been attributed to hyperinsulinemia, with resulting increases in sympathetic nervous system activity. However, recent data from our laboratory suggest that cellular insulin resistance rather than hyperinsulinemia per se may lead to hypertension. The basic tenet proposed in this article is that a deficiency of insulin at the cellular level represents a common mechanism that is involved in the development of hypertension in both type I and type II diabetes mellitus. Insulin has an important role in the modulation of cellular calcium metabolism. Decreased insulin action on vascular smooth muscle cells may contribute both to hypertension and to accelerated atherosclerosis. Recent observations suggest that an impaired cellular response to insulin predisposes to increased vascular smooth muscle tone (the hallmark of hypertension in the diabetic state). For example, recently reported studies from our laboratory demonstrate that insulin attenuates the vascular contractile response to phenylephrine, serotonin, and potassium chloride. Thus, it appears that insulin normally modulates (attenuates) vascular smooth muscle contractile responses to vasoactive factors, and insulin resistance should accordingly be associated with enhanced vascular reactivity.