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Thursday, March 18, 2010

Should ACCORD Results Challenge Treatment Guidelines for Type 2 Diabetes

Last week the New England Journal of Medicine published the most recent results from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial looking at blood pressure and lipid management in patients with type 2 Diabetes.

Published guidelines for diabetes treatment suggest that diabetic patients should be treated to a blood pressure goal of <130/80 to reduce the risk of cardiovascular and renal complications. The current published blood pressure guidelines for diabetes are based on two previous large clinical trials: the United Kingdom Prospective Diabetes Study, and a post-hoc subgroup analysis of the trial Hypertension Optimal Treatment study.

In last week’s ACCORD results, diabetic patients who were randomized to intensive blood pressure control (systolic blood pressure < 120) were compared with those with those treated to a standard treatment goal for blood pressure (systolic blood pressure < 140). Patients were followed for 5 years and there was no difference found in either fatal or non-fatal cardiovascular events between groups.

In the case of lipid treatment in diabetic patients, last week’s NEJM reported on the outcome of type 2 diabetic patients treated with a statin alone (simvastatin) versus those treated with a combination of simvastatin plus fenofibrate. Although the addition of the fenofibrate did result in lower triglyceride levels and higher HDL levels, the study showed no difference in cardiovascular outcomes between these groups, except in a subgroup of patients with the most profound dyslipidemia. In this subgroup mean HDL cholesterol was 30 and mean triglyceride level was 284.

What do these findings mean? The American Diabetes Association 2010 treatment guidelines for diabetes recommend treating diabetic patients to a goal of a systolic blood pressure <130. The ACCORD study treated patients to an even more aggressive goal (sbp <120). It seems the more aggressive goal should not be recommended. Whether or not we should relax our treatment goals for diabetic patients, to the same goals as the general population with hypertension (<140) remains in question, but the study provides evidence pointing in this direction.

Perhaps the most salient point, brought out by the lipid study, is that once again physicians should be skeptical about treating to particular numerical goals without clear evidence that these targets will translate to improved outcomes for patients. Although fenofibrate is clearly effective in lowering triglycerides and raising HDL, a positive impact of this effect in terms of actual outcomes was only seen in diabetics with more profound dyslipidemia.

The other limitations of the ACCORD study worth mentioning are that:
1. Patients were only followed for 5 years, and
2. The study population was high risk type 2 diabetics (>40 and cardiovascular disease, or >55 and two additional cardiovascular risk factors).

How these results translate to healthier type 2 diabetics treated in earlier stages of illness for longer periods of time remains unknown.

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