What should be the target hemoglobin A1c (HbA1c) values in patients with type 2 diabetes mellitus?
Victor M. Montori: The selection of HbA1c targets is something that I think is evolving. We have gone from a period where we have been very confident that lower HbA1c is better in terms of reducing the risk of diabetes complications [and that is clear when people have symptoms] to the current situation—perhaps up to HbA1c of around 8% or so [and without symptoms]. As for achieving HbA1c in a normal range, unfortunately we do not have any clinical trials that would suggest that people would be better off. Medications that can achieve lower HbA1c levels without, for instance, hypoglycemia may make that a compelling hypothesis to test in the future, but we do not know that now.
We know that the range is fairly broad—somewhere between 7% and 8% or 8.5%, where people may have HbA1c levels that may capture most of the benefits of glycemic control while keeping the burden of treatment—the treatment that we may use to try to lower HbA1c—under control. Most of my patients, I think, find themselves quite comfortable in the 6.5% to 7.5% range. But the most important thing that we talk about when we talk about goals is, “Are we overwhelming you with the treatment?” and, “Are you having low blood sugars?” If the treatment is tolerable, can be fit in the patient’s life, and we are not having or causing hypoglycemia, I think we are in a good place, and the lower HbA1c level that we can achieve while doing that, that is when we normally feel that we are ok.
We do not have a lot of good evidence, however, that glycemic control may be the most important thing to do in patients with diabetes. So we do not spend a lot of our time on HbA1c, we spend most of our time on looking at lifestyle, stress, smoking cessation, cardiovascular risk reduction, blood pressure control, kidney protection, and feet protection. HbA1c is just one of those things that we look into.