According to the article, type 2 diabetes and hypertension are often associated. At age 40, approximately 32 percent of patients with type 2 diabetes are also hypertensive, and that proportion increases to 47 percent by age 60, the article states. Hypertension also increases the risk of microvascular disease (including diseases of the eye like retinopathy, which can affect vision), and reducing blood pressure has been known to reduce the risk of microvascular disease.
David R. Matthews, F.R.C.P., of the Oxford Centre for Diabetes, Endocrinology, and Metabolism, Churchill Hospital, England, and colleagues investigated the relationship between tight blood pressure (BP) control and diabetic retinopathy (a type of eye disorder associated with diabetes) in patients with type 2 diabetes mellitus (DM).
The researchers studied 1,148 hypertensive patients (average age, 56) who had DM for an average duration of 2.6 years at the beginning of the study. Participants had an average BP of 160/94 millimeters of mercury (mm Hg). Seven hundred fifty eight patients were randomly assigned to the tight BP control group (aiming for a BP of less than 150/85 mm Hg), and 390 were assigned to a less stringent BP control policy (aiming for a BP of less than 180/105 mm Hg).
The researchers found that 4.5 years after the beginning of the study, 23.3 percent of participants in the tight BP control group experienced five or more microaneurysms (tiny dilated areas in the walls of the blood vessels of the eye) compared to 33.5 percent of the less tight BP control group. Additionally, there was an elevated risk of blindness in the less strict BP control group, although no participant went blind in both eyes over the study period.
"High BP is detrimental to each aspect of diabetic retinopathy and a tight BP control policy reduces the risk of clinical complications from diabetic eye disease," the authors write.
(Arch Ophthalmol. 2004;122:1631-1640. Available post-embargo at archophthalmol.com)
Editor's Note: This study was supported in part by major grants from the United Kingdom (UK) Medical Research Council, London, England; British Diabetic Association; the UK Department of Health, London; National Eye Institute, National Institute of Digestive, Diabetes, and Kidney Disease in the National Institutes of Health, Bethesda, Md.; the British Heart Foundation, London; Novo-Nordisk A/S, Copenhagen, Denmark; Bayer (Schweiz) AG, Zurich, Switzerland; Bristol-Myers Squibb, New York, N.Y.; Hoechst AG, Kehl, Germany; Eli Lilly & Co., Indianapolis, Ind.; Lipha and Farmitalia Carlo Erba, Milan, Italy.
Editorial: Is Intensive Management of Blood Pressure to Prevent Visual Loss in Persons With Type 2 Diabetes Indicated?
In an accompanying editorial, Ronald Klein, M.D., M.P.H., of the University of Wisconsin-Madison, writes, "The report in this month's issue describes the effect of blood pressure control on the incidence of specific retinal lesions, the need for photocoagulation [treatment for ocular microaneurysms], and visual outcomes. The new data show a highly significant reduction in incidence of [several eye disorders associated with diabetes] at 7.5 years of follow up. Loss of three lines of vision or more at nine years of follow-up was reduced by 47 percent in the tight control group compared to the less tight control group."
Dr. Klein writes that, "These findings clearly demonstrate the importance of lowering blood pressure to reduce the progression of retinopathy, incidence of macular edema, and loss of vision in persons with relatively short duration of type 2 diabetes and moderate to severe hypertension."
He concludes: "Ophthalmologists should tell their diabetic patients about the benefits of blood pressure control in reducing loss of vision from diabetic retinopathy and emphasize the need for routine monitoring of blood pressure (including measurements at each eye examination)."
(Arch Ophthalmol. 2004;122:1707-1709. Available post-embargo at archophthalmol.com)
Editor's Note: Supported by grants from the National Institute of Health, Bethesda, Md., and in part by Research to Prevent Blindness, New York, NY. Dr. Klein is a member of the Steering Committee of the DIRECT, a randomized clinical trial of blood pressure control supported by Astra-Zeneca.
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