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Tight blood sugar control or fibrates prevent retinopathy progression but not visual loss (ACCORD)

Clinical Question:
Does tight control of blood sugar, lipids, or blood pressure improve opthalmologic outcomes in patients with type 2 diabetes mellitus?

Bottom Line:
Tight glycemic control and the addition of a fibrate reduces the progression of retinopathy by 3 steps on a 17-step scale, but does not reduce the likelihood of developing moderate visual loss over 4 years of follow-up. It is vitally important to recall that the ACCORD study found that tight glycemic control increased mortality, severe hypoglycemic episodes, weight gain, and complaints of swelling. So, although these findings may be touted by some as evidence of the benefits of tight blood sugar control and fibrates, that benefit is limited to the 2 cubic inches that contain the patient's eyeballs, and even those benefits are more disease-oriented than patient-oriented. (LOE = 1b)

Reference:
ACCORD Study Group; ACCORD Eye Study Group, Chew EY, Ambrosius WT, et al. Effects of medical therapies on retinopathy progression in type 2 diabetes. N Engl J Med 2010;363(3):233-244.  [PMID:20587587]

Study Design:
Randomized controlled trial (single-blinded)

Funding:
Government

Allocation:
Concealed

Setting:
Outpatient (any)

Synopsis:
This is a substudy of the recent ACCORD trial that studied more control versus less control of blood pressure (< 140 vs < 120 mm Hg), lipids (fenofibrate plus simvastatin vs simvastatin alone), or blood sugar (< 6.0% vs 7.0%-7.9% glycohemoglobin). Of the 10,251 participants in the overall ACCORD trial, those with previously treated proliferative diabetic retinopathy at baseline were excluded. A subset of the remaining patients were enrolled in the ACCORD eye study; of the 3537 patients who were initially recruited, 4-year follow-up data was available for 2856 patients regarding the effect of tight blood sugar control, 1593 regarding the effect of fibrates, and 1263 regarding the effect of tight blood pressure control. The mean age of patients was 62 years, the mean duration of diabetes was 10 years, 38% were women, and 30% were of a nonwhite race. The average glycohemoglobin level at the start of the study was 8.2%, the average low-density lipoprotein level was 101, and the average blood pressure was 135/35 mm Hg. There were 2 primary outcomes: the development of moderate visual loss, and the progression of diabetic retinopathy of 3 steps or more on a standardized 17-step scale. The researchers found that tight control of blood sugar and lipids had no effect on moderate vision loss, with a possible trend toward worse outcomes with tight blood pressure control (19.4% vs 15.8%; P = .06). Strict glycemic control reduced the likelihood of progression of diabetic retinopathy (7.3% vs 10.4%; P = .003; number needed to treat [NNT] = 33), as did the addition of a fenofibrate (6.5% vs 10.7%; P = .006; NNT = 27). This is similar to the findings in the United Kingdom Prospective Diabetes Study, which found less need for laser photocoagulation in the tight control group. Also, the report of the full ACCORD population found a trend toward the prevention of moderate vision loss with tight glycemic control.

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