Patients with type 2 diabetes and hypertension who kept their blood pressure very tightly controlled had fewer eye disorders caused by their diabetes, according to an article in the November issue of The Archives of Ophthalmology, one of the JAMA/Archives journals.
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.