Considerable disturbances of cardiovascular risk factors in women with diabetes and myocardial infarction

Abstract

Objective

To investigate to which extent differences in cardiovascular risk factors explain the increased risk of myocardial infarction (MI) and complication rate in women with diabetes mellitus (DM).

Design

Case-control study.

Subjects

We compared women with diabetes and previous MI (n=29), diabetes but no MI (n=46), prior MI but no diabetes (n=64), and healthy controls (n=125).

Measurements

Smoking habits, physical activity, blood pressure (BP), body mass index (BMI), waist/hip ratio (WHR), serum lipids, plasma fibrinogen, and serum sex hormones.

Results

Despite the fact that diabetic women had similar BMI, those with a past MI, compared to diabetic women without MI, had significantly higher WHR (mean, 95% CI) [0.89 (0.87, 0.92) vs. 0.84 (0.81, 0.86) mmol/l, P=.001] and very high S-triglycerides [3.03 (2.23, 3.83) vs. 1.69, (1.39, 1.99) mmol/l, P=.001] and low HDL-cholesterol [1.09 (0.94, 1.24) vs. 1.56 (1.41, 1.71) mmol/l, P<.001], indicating pronounced metabolic disturbances. Women with MI but no diabetes had intermediate values for WHR, triglycerides, and HDL-cholesterol. Furthermore, women with diabetes and MI had significantly higher p-fibrinogen, were smokers, and lived a more sedentary life than the other women. Over half of all women with prior MI were on lipid-lowering therapy and tended to have nonsignificantly lower S-cholesterol than women without MI.

Conclusions

Women with diabetes who have manifested an MI carry a very substantial cardiovascular risk factor burden, which probably explain their increased morbidity and mortality. In order to improve prognosis, studies targeted at investigating treatment modalities for these abnormalities are needed.

Introduction

In addition to smoking, hypertension, and hyperlipidemia, diabetes mellitus (DM) is a strong risk factor for the development of cardiovascular disease (CVD). While the prevalence of diabetes is 3–4% in the general Swedish population Andersson et al., 1991, Eliasson et al., 2002, 20–25% of patients with myocardial infarction (MI) have known diabetes Abbud et al., 1995, Löwel et al., 2000, Lundberg et al., 1997, Malmberg et al., 2000, Norhammar et al., 2002. Consequently, a considerable amount of diabetic patients, numbers of 50–70% are usually given, are affected by CVD and especially coronary heart disease (CHD) during their life span. Previous studies have shown several times increased risk of primary and recurrent MI and of cardiovascular mortality in diabetic compared to nondiabetic subjects Abbott et al., 1988, Abbud et al., 1995, Adlerberth et al., 1998, Barrett-Connor et al., 1991, Chun et al., 1997, Haffner et al., 1998, Hanefeld et al., 1996, Kanaya et al., 2002, Krolewski et al., 1987, Lee et al., 2000, Lehto et al., 1994, Löwel et al., 2000, Malmberg et al., 2000, Miettinen et al., 1998, Ulvenstam et al., 1985, Vilbergsson et al., 1998.

During the last decades, mortality from CHD has declined in the Western populations. However, this improvement has not occurred in diabetic patients Chun et al., 1997, Gu et al., 1999. Furthermore, the difference in CHD morbidity and mortality between diabetic and nondiabetic individuals seems to be more prominent in women than in men Abbott et al., 1988, Barrett-Connor et al., 1991, Benderly, et al., for the SPRINT study group, 1997, Chun et al., 1997, Lee et al., 2000, Lehto et al., 1994, Malmberg et al., 2000, Miettinen et al., 1998, although conflicting results have been reported Abbud et al., 1995, Kanaya et al., 2002, Krolewski et al., 1987, Löwel et al., 2000, Vilbergsson et al., 1998. However, the inconsistent findings may be explained by different ways of analysing morbidity and mortality (Kanaya et al., 2002).

Women with diabetes surviving an MI appear to have a more unfavourable prognosis than diabetic men Abbott et al., 1988, Benderly, et al., for the SPRINT study group, 1997, Chun et al., 1997, although some studies did not show any major differences (Abbud et al., 1995). Some authors claim that DM, besides older age, is the main reason for the increased mortality in women surviving an MI (Benderly et al., 1997).

Infarct size does not differ or is smaller in diabetic compared to nondiabetic MI patients Lehto et al., 1994, Löwel et al., 2000, Miettinen et al., 1998. However, angiographic studies have shown a more severe and extensive type of coronary artery disease in patients with both types 1 and 2 diabetes compared to patients without diabetes, with particularly marked differences in women Natali et al., 2000, Pajunen et al., 2000. This might explain the increased incidence of congestive heart failure (CHF) in diabetic women Abbott et al., 1988, Lehto et al., 1994.

In previous studies, increased levels of serum total cholesterol, LDL-cholesterol, triglycerides (TG), and blood pressure (BP) and lower HDL-cholesterol were reported in diabetic compared to nondiabetic subjects. However, few studies have investigated to what extent major CHD risk factors contribute to the risk of MI in women with diabetes (Barrett-Connor et al., 1991). The aim of the present case-control study was to estimate the CHD risk factor burden in women with diabetes, MI, or both compared to healthy women and to investigate to what extent the differences in risk factors might explain the increased MI risk and complication rate in women with diabetes.