|ISSN No. 1606-7754 Vol.15 No.3 December 2007|
Study on the effect of oral hypoglycaemic agents on arterial stiffness among Malays with type II diabetes mellitus
N H Hassan1, J Shaaban1, A Abdul Kadir1, A Rehman2, A R Abdul Rahman3
Family Medicine Department, School of Medical Sciences 1 , School of Dental Sciences2, USM, 16150 Kubang Kerian, Kelantan, Cyberjaya University College of Medical Sciences3, 63000 Cyberjaya, Selangor, Malaysia
Objective: To determine the effect of two regimens of oral hypoglycaemic agents: sulphonylurea monotherapy and metformin in combination with sulphonylurea on arterial stiffness. Methods: A case control study was conducted at the Family Medicine and Diabetic Clinic, HUSM from May 2004 until May 2005. Sixty subjects receiving sulphonylurea alone and ninety subjects on combination therapy with metformin participated in this study. A simple random sampling method using a draw lot was used to select 51 subjects for each group. Augmentation index (AI) was measured using the Sphygmocor apparatus and all measurements were performed by the investigators after an earlier validation study. The mean augmentation index measurements were analyzed. Results: The mean AI values of diabetic subjects treated with sulphonylurea monotherapy and a combination with metformin were 140.51 ± 11.42 vs 140.14 ± 12.86, p= 0.877. AI values were significantly higher in females compared with males (143.23 ± 10.60 vs 135.82 ± 13.01, 95% CI: -12.07, -2.73, p = 0.002). Duration of diabetes (in years) was significantly less (3.46 ± 3.16 vs 5.41 ± 3.66, p = 0.005) for sulphonylurea monotherapy patients compared with combination therapy patients. Conclusion: This study shows that sulphonylurea monotherapy and metformin in combination with sulphonylurea have similar effects on arterial stiffness in type 2 diabetes subjects. Diabetes is associated with a greater arterial stiffness in women compared with men.
Key words: arterial stiffness, augmentation index, oral hypoglycemic agent
Insulin resistance and type 2 diabetes are major causes of morbidity and mortality in the industrialized world. It has been estimated that the prevalence of type 2 diabetes mellitus will increase from the present 160 million to 215 million by 2010.1 Of the patients diagnosed with myocardial infarction, about 20% have previously had type 2 diabetes.2
Arterial stiffness may become a major primary goal of treatment in patients at risk of cardiovascular disease. Drugs may improve the stiffness of the arterial wall through either functional or structural mechanisms.3
Arterial stiffness is determined by structural and functional components related to the intrinsic elastic properties of the artery. The endothelium, the elastic tissue within the intima media layer and smooth muscle contribute to arterial stiffness.4
The relationship between arterial stiffness as measured by pulse wave velocity (PWV) and the elastic properties of the arterial wall has been extensively studied.5 Radial artery pressure waveforms recorded with tonometry have been shown to equal those measured intra-arterially in a large group of healthy subjects.6 Several studies have now demonstrated that a single generalized transfer function can be used to determine accurately central from peripheral pressures in healthy subjects and in patients with a variety of diseases.7,8,9
In a study by Satoh et al, 10 it was demonstrated that treatment of patients with type 2 diabetes with pioglitazone for three months resulted in a significant decrease in PWV.10 This is in agreement with other studies which reported that intima media thickness (IMT) was significantly reduced in type 2 diabetic patients administered troglitazone or pioglitazone for three months.11, 12
However, there is lack of clinical data on the effect of conventional oral hypoglycemic agents, like metformin or sulfonylurea or a combination of both, on arterial stiffness in patients with type 2 diabetes mellitus although there is a study showing that treatment with metformin for 12 weeks improved endothelial function.13
The aim of the study was to examine combined oral hypoglycaemic agent therapy on arterial stiffness in type 2 diabetes. Based on previous studies, this study also took three months as a minimum duration for taking the oral hypoglycaemic agent(s).