ISSN No. 1606-7754                   Vol.17 No.2 August 2009
Gender: does it have a role in blood pressure in Caucasians with well-controlled type 2 diabetes?
Barre DE, Mizier-Barre KA, GrisctiO, Hafez, K
Department of Health Studies,Cape Breton University, Sydney, Nova Scotia, Canada
Abstract

Background: Blood pressures are increased in type 2 diabetics presenting an enhanced risk of myocardial infarction and subsequent death. It is controversial whether males have a greater risk of myocardial infarction and resultant death in type 2 diabetes. Objective: The purpose of this study was to review the literature regarding gender in blood pressure and to test the hypothesis that there would be gender inequality in blood pressure in well-controlled Caucasian type 2 diabetics in Cape Breton, Nova Scotia resulting in at least one gender exceeding the Canadian Diabetes Association (CDA) guidelines for systolic and/or diastolic pressures. Methods: Blood pressure were done by sphygmomanometry and using a stethoscope. Results: This study revealed statistically identical blood pressures in males and females which were above the CDA guidelines for systolic and diastolic pressures. Conclusion: It is concluded that neither males nor females as a population in this study are meeting the CDA guidelines for systolic or diastolic pressures and as such may well be at greater risk of myocardial infarction than if they were meeting these CDA guidelines. Ultimately it will have to be determined what approaches are suitable in bringing blood pressures to clinical target endpoints and what role gender may play in these approaches to management of hypertension in type 2 diabetics. However, this was only a very small study and a much larger one would answer whether there is gender inequality in blood pressure among persons with well-controlled type 2 diabetes.

Keywords:

Blood pressure, type 2 diabetes, Gender

Introduction

Cape Breton Island in the province of Nova Scotia, Canada suffers from among the highest rates of type 2 diabetes in Canada, the consequence of which are seen in the overall economy and in the competition for healthcare dollars with other health issues. Consequently it is important to control this disease as much as possible so as to reduce its economic and social impact. There appear to be no reports regarding gender equity of management of blood pressure anywhere, such information being of clear importance for the medical, economic and social impacts of this disease.

Type 2 diabetes increases the risk of atherosclerosis-induced myocardial infarction and subsequent death.1,2,3 Myocardial infarction may result from the formation of thrombi and/or emboli in type 2 diabetics.4,5 It was hypothesized that as the preponderance of studies show a greater risk of myocardial infarction and subsequent death in male type 2 diabetics,6,7,8,9 there should be higher blood pressure in males. However, other studies show a greater risk of myocardial infarction and subsequent death in female type 2 diabetics.10,11,12 It has never been clear whether hypertension plays a role in gender differences in myocardial infarction incidence in type 2 diabetics. Ong et al.13 showed no gender difference in hypertension while Keyhani et al.14 showed females to be less likely to meeting blood pressure goals. However neither Ong et al.13 or Keyhani et al.14 specifically referred to type 2 diabetics.

Hypertension increases platelet aggregation, in part via damage to the arterial endothelium,15 which exposes platelets to vascular wall collagen.16,17 Increased platelet aggregation enhances the risk of myocardial infarction.18,19,20,21 22 Hypertension features in many type 2 diabetics23,24 along with an increase in platelet aggregability.25,26  However, no work has ever been done to assess potential gender difference in blood pressures in type 2 Caucasian diabetics. The purpose of this work was to determine if there was a significant difference between blood pressures in male versus female Caucasian type 2 diabetics that are well-controlled (< 8 % HbA1c) and if either or both genders are meeting the CDA guidelines for systolic and diastolic pressures.

Materials

Subjects (n =20 male, 20 female) were randomly chosen from among 84 Caucasians responding in approximately equal sex numbers to a Sydney, Nova Scotia newspaper advertisement and two area physicians.  This study received approval from the Cape Breton University Human Ethics Review Committee. Subjects came for visit 1 and 3 months later for visit 2. On both visits, body weight and height were determined. Blood pressure was measured by the same person for all patients using the same stethoscope and sphygmomanometer.

Statistical Analysis

The data in tables 1 and 2 was analysed by an unpaired t-test for male versus female for each of visits 1, 2, and the combined visits 1 and 2.  The data reflects patients who completed both visits 1 and 2. A paired t-test was performed for each gender for each of BMI (table 1) and for systolic and diastolic pressures (table 2) going from visit 1 to visit 2.

Results

Subject characteristics are contained in table 1. There were no significant differences in BMI between visits for males or females nor was there any difference between males and females in age or BMI for either visit 1 or 2. Blood pressures are found in table 2. Males had statistically identical blood pressures compared to females (visit 1, visit 2, and visits 1 and 2 combined). There were no differences in blood pressures going from visit 1 to visit 2 for either gender.

Discussion

Platelet function and activation16,17 are reflected in blood pressure. The reduction of blood pressure results in lower platelet activation27 and risk of other cardiovascular complications.28

The blood pressure data is validated by its consistency between visits one and two. The subjects of this study, each by gender population, are not meeting the Canadian Diabetes Association (CDA) 2003 guidelines29 for systolic (< 130 mm Hg) and diastolic (< 80 mm Hg) pressures. This appears to be the first study addressing gender and hypertension in type 2 diabetics.

Thus, it seems that males may be in no greater need of intervention or intensity of intervention30  to decrease blood pressures than females and that both require intervention to overcome this risk factor for myocardial infarction and potential subsequent death. Weight reduction is an important feature in blood pressure reduction31,32 and certainly as a population the persons involved in the current study are obese as assessed by BMI.  Wan et al33 have indicated that individuals with a high BMI have worse (elevated) systolic pressures. However regardless of the method(s) used to reduce hypertension, Osher and Stern34 have cautioned that getting systolic pressures to less than 130 mm Hg may be associated with diastolic hypotension. Regardless, Bebb et al35 have observed that it appears very difficult at the present time to meet the CDA targets though intensive intervention did improve target achievement in one study.36

The current study was only a very small study and a much larger one would answer whether there is gender inequality in blood pressure among persons with well-controlled Caucasian type 2 diabetes. The role of gender and dose in any in specific blood pressure intervention threshold also remains to be determined.

In conclusion, Caucasian type 2 diabetic males may require no more aggressive intervention to decrease blood pressures than do Caucasian type 2 diabetic females. It would appear that hypertension may play no role in gender differences in myocardial infarction incidence in Caucasian type 2 diabetics. However, both sexes continue to have hypertension as defined by the CDA and this presents an enhance risk of myocardial infarction and potential subsequent death.

Acknowledgement

Ms. Pat Collins, R.N. of the Cape Breton University Health Centre is thanked for help with blood taking and anthropometric measures. The authors also acknowledge the contribution of Dr. J. Wawrzyszyn of Sydney for drawing this study to the attention of his patients. We also thank    Dr. E. Rudiuk of Cape Breton University for his assistance with statistical analyses.