Postmenopausal estrogens and risk of myocardial infarction in diabetic women

Sex-gender-related therapeutic approaches for cardiovascular complications associated with diabetes

Diabetes is a chronic disease associated with micro- and macrovascular complications and is a well-established risk factor for cardiovascular disease. Cardiovascular complications associated with diabetes are among the most important causes of death in diabetic patients. Interestingly, several sex-gender differences have been reported to significantly impact in the pathophysiology of diabetes. In particular, sex-gender differences have been reported to affect diabetes epidemiology, risk factors, as well as cardiovascular complications associated with diabetes. This suggests that different therapeutic approaches are needed for managing diabetes-associated cardiovascular complications in men and women. In this review, we will discuss about the sex-gender differences that are known to impact on diabetes, mainly focusing on the cardiovascular complications associated with the disease. We will then discuss the therapeutic approaches for managing diabetes-associated cardiovascular complications and how differences in sex-gender can influence the existing therapeutic approaches.

Effects of low-dose continuous combined hormone replacement therapy on glucose homeostasis and markers of cardiovascular risk in women with type 2 diabetes

BACKGROUND

Low-dose hormone replacement therapy (HRT) has attracted interest for the treatment of postmenopausal symptoms in diabetes because of concerns about increased risk of coronary heart disease (CHD) and stroke with conventional HRT containing conjugated equine oestrogens (CEEs) and medroxyprogesterone acetate (MPA).

OBJECTIVES

We assessed the effects on glucose homeostasis and cardiovascular risk factors of continuous oral 17beta oestradiol (1 mg) and norethisterone (0.5 mg) in postmenopausal women with type 2 diabetes.

DESIGN

Double-blind, randomized placebo-controlled trial.

ASSESSMENTS

Hyperinsulinaemic isoglycaemic clamp and cardiovascular risk factors were assessed before and after 3 months of treatment.

RESULTS

Twenty-eight women completed the study. HRT decreased fasting glucose compared with placebo [-9.4% with HRT vs.+2.3% for placebo, 95% confidence interval (CI) -23.2 to -0.3] and total cholesterol (-13.7 vs.+1.0%, 95% CI -22.4 to -3.1%) No significant effect was seen on metabolic clearance rate of glucose, glycated haemoglobin (HbA1c), triglycerides, high density lipoprotein (HDL)-cholesterol or C-reactive protein (CRP).

CONCLUSIONS

In women with type 2 diabetes, low-dose HRT decreased fasting glucose and total cholesterol without detectable adverse effects on glucose clearance, triglycerides and CRP as reported with conventional HRT.

Gender-specific care of the patient with diabetes: review and recommendations

BACKGROUND

Men and women differ in their experience of diabetes mellitus (DM). For optimal prevention and treatment of the disease, these differences must be acknowledged. Unfortunately, most studies of diabetes have focused almost exclusively on men.

OBJECTIVE

The purpose of this review was to survey the literature about the sex-specific features of DM and to make recommendations for the gender-specific care of patients.

METHODS

An initial literature search was performed with Google Scholar and MEDLINE (1995-2005) using the search terms sex/gender, women, diabetes mellitus, and coronary artery disease, and specific topic headings such as polycystic ovary syndrome. The bibliographies of articles were used extensively to augment the search, and more specific search terms were included. The strength of each recommendation was assessed.

RESULTS

: Even when women were included in clinical trials, investigators typically made no attempt to assess the impact of sex differences on the reported results. Existing studies, however, reveal several differences between men and women with diabetes. The prevalence of DM is growing fastest for older minority women. Women with diabetes, regardless of menopausal status, have a 4- to 6-fold increase in the risk of developing coronary artery disease (CAD), whereas men with diabetes have a 2- to 3-fold increase in risk. Women with diabetes have a poorer prognosis after myocardial infarction and a higher risk of death overall from cardiovascular disease than do men with diabetes. Women with type 2 DM experience more symptoms of hyperglycemia than do their male counterparts. Obesity, an important contributor to type 2 DM, is more prevalent in women. Women with diabetes have an increased risk of hypertension compared with men with diabetes. Women have a more severe type of dyslipidemia than do men (low levels of high-density lipoprotein cholesterol, small particle size of low-density lipoprotein cholesterol, and high levels of triglycerides), and these risk factors for CAD have a stronger influence in women. Oxidative stress may confer a greater increase in the risk of CAD for women with diabetes than for men with diabetes. Many other sex differences in DM are due to women's reproductive physiology. Polycystic ovary syndrome is an important correlate of insulin resistance and the metabolic syndrome. Gestational diabetes mellitus (GDM) increases the risk of cardiovascular disease and type 2 DM. Women are less likely than men to receive aggressive treatment for CAD and to achieve treatment goals. Critical recommendations for women include exercise, testing for CAD, daily aspirin to counteract the prothrombotic state, depression screening, careful treatment to avoid weight gain, long-term follow-up of children of women with GDM, control of risk factors for CAD, and aggressive treatment with coronary angioplasty for CAD. Disease management programs for patients with diabetes have been shown to save money and improve outcomes, and should continue to incorporate information about sex-specific differences in DM as it becomes available.

CONCLUSION

Gender-specific care of the patient with diabetes should be informed by evidence-based recommendations.

Hormone replacement therapy and risk of acute myocardial infarction : a review of the literature

Many animal studies and studies on intermediate clinical endpoints have shown hormone replacement therapy (HRT) to be associated with both favourable and unfavourable cardiovascular effects. We reviewed the literature regarding HRT and the distinct endpoint of acute myocardial infarction (AMI) in peri- and postmenopausal women. Searches of the MEDLINE and EMBASE databases were conducted. Fifty papers were identified as eligible for inclusion: eight randomised controlled trials, 18 cohort studies, 23 case-control studies and one case-control and cohort study. The single large primary prevention randomised controlled trial on HRT and the risk of AMI in generally healthy women (Women's Health Initiative trial) reported a small yet significantly increased risk of AMI in postmenopausal women receiving combined HRT. This contrasts with a large number of observational studies that suggested a protective effect, although in many of these studies the results were not statistically significant. Inconclusive evidence on the effect of duration of use does not support the notion that a possible protective association is causal. Detection bias and residual confounding are alternative explanations for the associations observed in the randomised controlled trial and observational studies. No studies on groups of women with existing cardiovascular disease or with diabetes mellitus, including the only large secondary prevention trial (Heart and Estrogen/Progestin Replacement Study), reported a significant change in AMI risk between HRT users and non-users. There is insufficient evidence to suggest that HRT is associated with a change in the risk of AMI in the majority of women. However, certain subgroups of women with specific genetic polymorphisms may be more susceptible to a change in the risk of AMI with HRT use.

Use, intentions, and beliefs about hormone replacement therapy in women with and without diabetes

OBJECTIVES

(1) Describe women's (a) hormone replacement therapy (HRT) use patterns, (b) intentions to use or continue to use HRT among women in the early and late stages of menopause, and (c) beliefs about using HRT and (2) compare these beliefs, patterns, and intentions between women with and without diabetes 10-12 months after news from the women's health initiative was widely publicized.

METHODS

A survey mailed to female enrollees of a not-for-profit managed care organization (MCO) between 46 and 60 years of age and with or without diabetes. Descriptive statistics were calculated. Chi-square analysis was used to determine significant differences between four different HRT use and menopause stage groups, (1) early stage never user, (2) late stage never user, (3) late stage current user, and (4) late stage previous user. Analysis of variance (ANOVA) was used to identify significant belief differences between the four groups. Repeated-measures ANOVA was performed to examine differences between women with and without diabetes.

RESULTS

Most women did not intend to initiate HRT. About 86% of current HRT users intended to continue. Never users with diabetes were significantly more uncertain about HRT intention than non-diabetic women. All beliefs were significantly different (p<0.001) between the four groups, but not between women with and without diabetes.

CONCLUSION

Women in different groups hold different beliefs about HRT use. Uncertainty among women with diabetes is not resolved as quickly as among women without diabetes.

Hormone replacement therapy and cardiovascular risk

Hormone replacement therapy (HRT) is effective in suppressing postmenopausal symptoms and, in the past, many have claimed that it is cardioprotective. It was thought that the lower incidence of cardiovascular disease in premenopausal women was related to the cardioprotective effect of estrogen. Many of these studies were, however, observational studies. HRT alters many cardiovascular parameters, most beneficially. The mixed effect on these parameters make the overall result on cardiovascular risk difficult to predict. However, recent randomized, placebo-controlled trials have shown not only that HRT does not confer cardioprotection, but that it actually increases one's cardiovascular risk in the short term. Based on the current evidence, HRT should not be recommended in the hope that it will protect postmenopausal women against coronary heart disease.

Sex hormones, insulin sensitivity, and diabetes mellitus

Sex differences and the role of gonadal hormones in modulating insulin sensitivity and glucose tolerance are of increasing interest and importance because of the increasing prevalence of type 2 diabetes mellitus and the metabolic abnormalities associated with aging. Body composition is closely associated with insulin sensitivity, and increased body fat, particularly in the visceral compartment, is a risk factor for developing type 2 diabetes mellitus. Sex differences in body composition and/or insulin sensitivity are evident in humans throughout the lifespan. Ovarian hormones influence insulin sensitivity across the menstrual cycle, during pregnancy, and in the menopausal transition. Similarly, estrogens and progestins used for contraception and hormone replacement therapy affect glucoregulation. Nonhuman primates and humans have similar life histories and reproductive characteristics. As a result, nonhuman primates provide a valuable model for investigating factors related to insulin sensitivity. Studies of nonhuman primates have contributed significantly to our understanding of sex differences and the influence of sex steroids in this context. This brief review surveys present knowledge of the sex differences in body composition, insulin sensitivity, and risk for development of type 2 diabetes mellitus derived from studies in humans and nonhuman primates. The influences of endogenous and exogenous gonadal steroids are emphasized.

Effect of hormone replacement therapy on cardiovascular risk factors in postmenopausal women with diabetes

BACKGROUND

Hormone replacement therapy (HRT) in postmenopausal women improves menopausal symptoms, decreases the incidence of osteoporotic fracture, but the effects on cardiovascular risk factors remain controversial.

AIM

To test the hypothesis that HRT may have beneficial effects on the cardiovascular risk profile in postmenopausal women with diabetes.

METHODS

One hundred and fifty postmenopausal patients with type 1 (T1DM) and type 2 diabetes (T2DM) were randomized to receive HRT (Kliofem) or placebo for 12 months. We monitored the effects on cardiovascular risk factors, including lipid profile, glycaemic control, blood pressure and body weight.

RESULTS

Mean low-density lipoprotein (LDL) cholesterol was associated with a nonsignificant decrease [-0.14 mmol/l (CI=-0.44, 0.17) (p=0.37)] in the Kliofem-treated group. Total cholesterol fell by 0.42 mmol/l (CI=-0.78, -0.05) (p=0.027). High-density lipoprotein (HDL) cholesterol was reduced by a mean of 0.07 mmol/l compared to a mean rise of 0.12 mmol/l on placebo. There were apparent differences in the treatment effects between T1DM and T2DM. There was no change in triglycerides or apoprotein B and no effect on glycaemic control, blood pressure or menopausal symptom scores. In the Kliofem group, BMI fell by 0.66 kg/m2 compared to an increase of 0.14 kg/m2 for placebo patients (p=0.046).

CONCLUSIONS

Although the long-term effects of HRT in women with or without diabetes appear to suggest that some types of HRT either confer no cardiovascular protection or may increase risk, the impact of Kliofem diabetic women on cardiovascular risk factors is probably neutral.

Estrogen therapy and risk of cardiovascular events among women with type 2 diabetes

OBJECTIVE

To evaluate the association between estrogen therapy and cardiovascular disease risk among women with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A retrospective, case-cohort study was conducted among 6017 women aged 45-80 years with type 2 diabetes from 1 January 1986 to 31 December 1992 at the Group Health Cooperative in Washington state. Cardiovascular outcomes, including nonfatal myocardial infarction (n = 215), coronary revascularization (n = 253), and cardiovascular deaths (n = 229), were ascertained through 31 December 1998. Use of estrogen and progestin was derived from automated pharmacy records and modeled as a time-dependent variable. Median follow-up was 6.8 years. Multivariable-adjusted relative risk (RR) and 95% CI were calculated using Cox proportional hazard models for case-cohort analyses.

RESULTS

Current use of estrogen with (RR 0.43, 95% CI 0.22-0.85) or without (0.48, 0.30-0.78) progestin was associated with a decreased risk of cardiovascular events compared with never having used estrogen. Risk of cardiovascular events associated with a first episode of estrogen use (with or without progestin) of <25 months' duration (1.12, 0.49-2.54), first episode of use >or=25 months' duration (0.32, 0.06-1.70), and current use that was not the first episode of use (0.42, 0.42-0.67) indicated that recent initiation was not associated with an increase or decrease in risk.

CONCLUSIONS

These results show an association of estrogen therapy, with or without progestin, with decreased risk of cardiovascular events among women with type 2 diabetes. This association should be further investigated in large randomized, controlled trials.

Hispanic women's experience with "el cambio de vida"

PURPOSE

To examine the factors that influence Hispanic women's decisions to initiate or not initiate hormone replacement therapy (HRT) during menopause to manage symptoms or to prevent longer-term conditions.

DATA SOURCES

A descriptive study of 51 Hispanic women who completed the Spanish version of the Menopausal Decision-Making Questionnaire (S-MDMQ) to describe their experience with and perceptions about menopause.

CONCLUSIONS

Most of the low-income Hispanic women in this study would elect not to take HRT; however, they do use exercise, diet, vitamins, and other self-care activities to manage symptoms of menopause. Hispanic women were eager to discuss how to manage their health care during perimenopause and menopause with one another and their health care providers.

IMPLICATIONS FOR PRACTICE

Nurse practitioners need to understand factors that might influence Hispanic women's decisions regarding management of menopausal symptoms, including the use of HRT, and to be able to assist women in making an individualized personal treatment choice that is culturally acceptable.

Current use of unopposed estrogen and estrogen plus progestin and the risk of acute myocardial infarction among women with diabetes: the Northern California Kaiser Permanente Diabetes Registry, 1995-1998

BACKGROUND

Little is known about hormone replacement therapy (HRT) and risk for myocardial infarction (MI) in diabetic women. We examined associations of current HRT, estrogen dosage, and time since HRT initiation with risk of acute MI in diabetic women.

METHODS AND RESULTS

Cox proportional hazards models, with current HRT modeled as a time-dependent covariate, were used to assess the 3-year risk of MI. Among 24 420 women without a recent MI (mean age 64.9 years), 1110 incident MIs were identified. After adjustment for cardiovascular risk factors, current HRT was associated with reduced MI risk (relative hazard [RH] 0.84, 95% CI 0.72 to 0.98). The RH for MI associated with current estrogen plus progestin use was 0.77 (95% CI 0.61 to 0.97), and the RH for MI associated with current unopposed estrogen use was 0.88 (95% CI 0.73 to 1.05). Women were at reduced MI risk if they were taking a low or medium dose of estrogen (equivalent to <0.625 or 0.625 mg of conjugated estrogen, respectively) but not a high dose (>0.625 mg of conjugated estrogen or its equivalent). Among those whose current use of HRT was <1 year, the RH for MI was 1.03 (95% CI 0.74 to 1.44), whereas among users for > or =1 year, the RH was 0.81 (95% CI 0.66 to 1.00). Among 580 women with a recent MI (mean age 69.2 years), 89 recurrent MIs were identified. An increased risk of recurrent MI was observed among current HRT users (RH 1.78, 95% CI 1.06 to 2.98), which was higher among those with current use for <1 year (RH 3.84, 95% CI 1.60 to 9.20).

CONCLUSIONS

In women without a recent MI, use of estrogen plus progestin was associated with decreased risk of MI. However, HRT was associated with increased risk of MI in women with history of a recent MI. Data from clinical trials in diabetic women are needed.

Effect of hormone replacement therapy on inflammation-sensitive proteins in post-menopausal women with Type 2 diabetes

AIMS

To test the effect of oral hormone replacement therapy (HRT) on plasma C-reactive protein (CRP), soluble vascular cell adhesion molecule-1 (VCAM-1), soluble intercellular adhesion molecule-1 (ICAM-1) and IL-6 concentrations and leucocyte count in post-menopausal women with Type 2 diabetes.

METHODS

Post-menopausal women with Type 2 diabetes (n = 61) were randomized in a double-blind fashion to receive either continuous combined hormone replacement therapy (n = 29) with conjugated equine oestrogen (0.625 mg/day) plus medroxyprogesterone acetate (2.5 mg/day) or placebo (n = 32) for 6 months. Study variables were measured at baseline and at the end of the study.

RESULTS

Eight women randomized to hormone replacement therapy and four women assigned to placebo group dropped out of the study. Plasma CRP increased (2.2 mg/l, 95% confidence interval 0.3-4.1 mg/l) significantly (P = 0.02) in women treated with HRT (n = 21) compared with placebo (n = 29) taking baseline CRP, body mass index (BMI) and smoking status into account. Plasma levels of cell adhesion molecules, IL-6 and leucocyte count did not change significantly during the study.

CONCLUSIONS

These findings indicate that oral HRT with conjugated equine oestrogen plus medroxyprogesterone acetate increases plasma CRP levels but not necessarily global inflammatory activity in post-menopausal diabetic women. An increase in plasma CRP may potentially increase risk of a cardiovascular event.

Estrogen has opposing effects on vascular reactivity in obese, insulin-resistant male Zucker rats

We hypothesized that estradiol treatment would improve vascular dysfunction commonly associated with obesity, hyperlipidemia, and insulin resistance. A sham operation or 17beta-estradiol pellet implantation was performed in male lean and obese Zucker rats. Maximal vasoconstriction (VC) to phenylephrine (PE) and potassium chloride was exaggerated in control obese rats compared with lean rats, but estradiol significantly attenuated VC in the obese rats. Estradiol reduced the PE EC50 in all groups. This effect was cyclooxygenase independent, because preincubation with indomethacin reduced VC response to PE similarly in a subset of control and estrogen-treated lean rats. Endothelium-independent vasodilation (VD) to sodium nitroprusside was similar among groups, but endothelium-dependent VD to ACh was significantly impaired in obese compared with lean rats. Estradiol improved VD in lean and obese rats by decreasing EC50 but impaired function by decreasing maximal VD. The shift in EC50 corresponded to an upregulation in nitric oxide synthase III protein expression in the aorta of the estrogen-treated obese rats. In summary, estrogen treatment improves vascular function in male insulin-resistant, obese rats, partially via an upregulation of nitric oxide synthase III protein expression. These effects are counteracted by adverse factors, such as hyperlipidemia and, potentially, a release of an endothelium-derived contractile agent.

The use of hormone replacement therapy in postmenopausal women with type 2 diabetes

In healthy postmenopausal women, estrogen or hormone replacement therapy (ERT or HRT) can alleviate menopausal symptoms and prevent osteoporosis and may also protect against cardiovascular disease (CVD). In addition to improving lipid metabolism, there are reports that estrogen also improves parameters regulating carbohydrate metabolism, including insulin resistance, in healthy women. Therefore, it is likely that ERT or HRT would also benefit women with type 2 diabetes, not only in relieving menopausal symptoms but also in improving the metabolic abnormalities associated with diabetes and in preventing cardiovascular disease.

Controversial issues in climacteric medicine I. Cardiovascular disease and hormone replacement therapy. International Menopause Society Expert Workshop. 13-16 October 2000, royal society of medicine, London, UK

The clinical benefits of HRT are clearly established for the relief of menopausal symptoms, improving quality of life and the prevention of osteoporosis. Although research on the impact of HRT (oral, transdermal, tibolone, etc.) and on the effects of raloxifene on CVD is still ongoing, with certain unresolved controversies, studies using a variety of different HRT formulations have shown a clear benefit on surrogate markers of CHD and epidemiological and clinical, although not randomized, studies have demonstrated a CHD reduction in HRT-treated women. Today, HRT may be used for the primary prevention of CVD. Conversely, there is no clear reason to commence HRT solely or primarily to confer an immediate cardiovascular benefit in postmenopausal women with established CHD. Equally, there is no compelling evidence for discontinuing--or indeed not initiating--HRT in women without CVD because of concern about cardiovascular risk. In any case, all medical interventions should be individualized to the specific woman's age, characteristics and needs. The ultimate effects of different dosages, schedules and type of hormones used should be clarified, avoiding inferring the effects of one form of HRT to others. The importance of increased attention to life-style factors such as healthy diet, exercise and cessation of smoking should be underlined since these can confer specific benefits also to menopausal women. For women with known risks for CVD, HRT may contribute to the beneficial effects of life-style improvements and well-established therapies (including blood pressure control, cholesterol-lowering drugs, aspirin, etc.). New strategies, including lower dosages, new estrogens, progestins, and new estrogen-like substances may be designed to target specific needs.

Hormone replacement therapy and incidence of acute myocardial infarction. A population-based nested case-control study

BACKGROUND

Epidemiological studies suggest a decreased risk of coronary heart disease (CHD) in healthy women taking hormonal replacement therapy (HRT). Whether this effect is shared by oral and transdermal preparations is unknown.

METHODS AND RESULTS

We conducted a population-based case-control study nested in a cohort of women 50 to 74 years of age without cardiovascular disease history in the United Kingdom. Among 164 769 women from the General Practice Research Database (January 1, 1991, to December 31, 1995), we identified 1242 first acute myocardial infarctions (AMI) and confirmed 1013 after medical record review. We randomly selected 5000 age-frequency-matched control subjects. AMI incidence was 1.6 per 1000 person-years; 13% and 17% of cases and control subjects used HRT within 6 months before the index date. Risk factor and comorbidity-adjusted OR of AMI for current-recent HRT users compared with nonusers was 0.72 (95% CI 0.59 to 0.89). The OR was similar within 30 days before the index date. The beneficial effect was present after 1 year of use (OR 0. 68; 95% CI 0.53 to 0.86), with no increase in risk within the first year. ORs for unopposed and opposed therapy were 0.52 (95% CI 0.35 to 0.78) and 0.79 (95% CI 0. 59 to 1.08); 79% and 21% used oral and transdermal therapy. The protective effect was present at medium-high doses of estrogens with ORs for oral and transdermal therapy of 0.63 (95% CI 0.46 to 0.86) and 0.62 (95% CI 0.37 to 1.06) and ceased after 2 to 3 years since stopping HRT.

CONCLUSIONS

Results are consistent with those previously reported in women without CHD who were taking oral HRT and, although based on few users, suggest that transdermal therapy might have similar cardioprotective effects.

Lipoproteins and low-dose estradiol replacement therapy in post-menopausal Type 2 diabetic patients: the effect of addition of norethisterone acetate

AIMS

Low-dose continuous oestrogen/progestogen may increase patient compliance long-term but the cardioprotective effects in diabetes are unknown. The aim of this study was to compare the effect of low-dose oral oestrogen (1 mg, 17-beta-estradiol) treatment with oestrogen (1 mg 17-beta-estradiol) in combination with low-dose (0.5 mg) continuous norethisterone acetate (NETA) on lipoproteins in Type 2 diabetic patients.

METHODS

Thirty-four post-menopausal Type 2 diabetic patients in moderate control (mean haemoglobin A1c 7.7%) who had a serum oestradiol level of < 50 pg/ml were examined over a 6-month period. Serum lipids, and lipoprotein composition of very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) were measured. Serum lipoprotein(a) was determined by an ELISA method, LDL fatty acids by gas-liquid chromatography and LDL oxidizability by thiobarbituric acid reactive substances (TBARS assay). Cholesteryl ester transfer protein (CETP), and cell cholesterol were measured.

RESULTS

There was a reduction in serum cholesterol on both treatments but no significant difference between treatment groups. LDL cholesterol decreased by 17% in each group. There was a no significant difference between the groups in serum VLDL or HDL cholesterol or serum triglycerides during the study. The change in lipoprotein(a) during the study was not significantly different between the groups. There was no significant difference in 4 h LDL oxidizability between groups. Although CETP increased with time in both groups there was no significant difference in the change between the groups.

CONCLUSION

In this small study, the addition of continuous low-dose NETA did not reduce the potentially beneficial effects of low-dose 17-beta-estradiol on the progression of atherosclerosis in diabetes.

Hormone replacement therapy and coronary heart disease. A new debate

Hormone replacement therapy is extensively used in the United States, especially for the possible prevention of heart disease, osteoporotic fractures, and, more recently, dementia. The results of recent clinical trials have raised new questions about the risk and benefits of estrogen or estrogen/progesterone therapy to prevent heart attacks, the choice of specific drug therapy such as specialized estrogen receptor modulation (SERM). The change in risk factors, especially weight gain or obesity, may determine the risks and benefits of hormone replacement therapy.

Hormone replacement therapy and intima-media thickness of the common carotid artery: the Rotterdam study

BACKGROUND AND PURPOSE

Observational data suggest that hormone replacement therapy (HRT) reduces morbidity and mortality from cardiovascular disease in healthy postmenopausal women. The mechanisms underlying this protection are not entirely clear but may include inhibition of the atherosclerotic process.

METHODS

We studied the association between ever use of HRT and intima-media thickness (IMT) of the common carotid artery in 1103 naturally menopausal women, aged 55 to 80 years, in the Rotterdam Study, a community-based cohort study in a suburban area of Rotterdam, Netherlands. Mean and maximum IMT of the common carotid artery were measured noninvasively with B-mode ultrasound.

RESULTS

Ever use of HRT for >/=1 year was associated with a decreased mean and maximum IMT compared with never users (mean IMT, 0.719 mm [SE 0.01] versus 0. 742 mm [SE 0.004], P=0.03; maximum IMT, 0.952 mm [SE 0.015] versus 0. 983 mm [SE 0.006], P=0.04), after adjustment for age, smoking, educational level, systolic blood pressure, and body mass index. No association was found for use <1 year (mean IMT, 0.739 mm [SE 0.013] versus 0.742 mm [SE 0.004], P=0.69; maximum IMT, 0.990 mm [SE 0.019] versus 0.983 mm [SE 0.006], P=0.75). Additional adjustment for diabetes, frequency of visits to healthcare facilities, or total and HDL cholesterol did not change these results.

CONCLUSIONS

The findings of this population-based study show that ever use of HRT is associated with a decreased IMT in the common carotid artery in elderly women.

Increased Ability of LDL from Normolipidemic Type 2 Diabetic Women to Generate Peroxides

Background: We assessed the ability of LDL from 30 type 1 diabetic patients (18 men, 12 women), 65 type 2 diabetic patients (35 men, 30 women), and 35 controls (19 men, 16 women) to generate peroxides. The men and women in the diabetic groups were studied separately and matched for age, body mass index, duration of diabetes, glycohemoglobin, and conventional lipid characteristics according to the presence or absence of hyperlipidemia.

Methods: The ability of LDL to form peroxides was assessed by measuring the thiobarbituric acid-reactive substances corrected for LDL-cholesterol [ratio of malondialdehyde (MDA) to LDL-cholesterol]. LDL particle size was expressed as the ratio of LDL-cholesterol to apolipoprotein B (LDL-cholesterol/apoB).

Results: The MDA/LDL-cholesterol ratio was higher in type 1 and type 2 diabetic patients with hyperlipidemia than in controls. The MDA/LDL-cholesterol ratio was also higher in type 2 normolipidemic women than in controls (P &lt;0.01). The LDL-cholesterol/apoB ratio was lower in type 2 diabetic women than in type 2 diabetic men (P &lt;0.05). The MDA/LDL-cholesterol ratio was negatively correlated with the LDL-cholesterol/apoB ratio (r = −0.78, P &lt;0.001) in hyperlipidemic type 1 (not type 2) diabetic patients. In normolipidemic type 2 diabetic patients, the MDA/LDL-cholesterol ratio was also negatively correlated with the LDL-cholesterol/apoB ratio (r = −0.75, P &lt;0.001) because of the highly significant negative correlation in type 2 diabetic women (r = −0.89, P &lt;0.01).

Conclusions: LDL from well-controlled type 2 diabetic women is smaller and more prone to form peroxides. This could explain why diabetic women are at greater risk of cardiovascular disease.

Cardiovascular disease in the diabetic woman

The incidence of cardiovascular disease (CVD) with age is increasing in the United States, and elderly women constitute a disproportional component of the aging population. Elderly women also have a relatively high incidence of diabetes, which contributes to this relatively high CVD risk. Although CVD is less common in premenopausal women than in men, this difference begins to disappear after the onset of menopause, presumably related to decreased levels of female sex hormones (estrogen and/or progesterone). Diabetes mellitus removes the normal premenopausal gender-related differences in the prevalence of CVD by mechanisms that are not clearly defined, including metabolic and hemodynamic factors associated with diabetes. Dyslipidemia in diabetes mellitus consists of low high density lipoprotein cholesterol, elevated triglyceride levels, and a small, dense, more atherogenic low density lipoprotein particle (i.e. oxidized). Dyslipidemia interacts with associated hemodynamic (i.e. hypertension) and metabolic abnormalities (i.e. increased platelet aggregation and plasminogen activator inhibitor-1 levels) to promote CVD risks in diabetic women. Recent controlled trials underscore the critical importance of aggressively treating CVD risk factors, especially dyslipidemia, in women with diabetes.