Diabetes Forecast

Tight Blood Glucose Management Benefits Heart and Longevity

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What to Know

If you have type 2 diabetes, you can protect yourself from complications such as vision loss from diabetes damage to the eyes (retinopathy) and nerve damage (neuropathy) by getting and keeping your A1C (a measure of your blood glucose levels over the previous three months) below 7 percent, the level recommended for most adults (although your safe range may be higher or lower) by the American Diabetes Association. But does tight control of A1C levels offer protection against heart attack, stroke, and early death? That’s less clear. This study investigated the long-term benefits of reducing A1C levels within six months of starting treatment for type 2 diabetes.

The Study

Danish researchers reviewed the health records of 24,752 adults with type 2 diabetes. Their average age was 63. The participants were grouped according to their A1C levels, as measured six months after they began to take metformin, the blood glucose–lowering drug doctors usually prescribe first after a type 2 diagnosis. The researchers also noted how much each participant’s A1C levels had dropped since treatment began. With that information in hand, the researchers then followed each participant for an average of about 2½ years to see how many had died or had had a heart attack or stroke.

The Results

Compared with participants whose A1C levels decreased to below 6.5 percent within six months of starting metformin, those whose A1C levels ranged from 6.5 percent to 6.99 percent had an 18 percent higher risk of early death, heart attack, or stroke. That risk of death or heart or brain injury increased as A1C levels increased, up to 59 percent for those with an A1C of 8 percent or higher. A big drop in A1C also offered protection. Participants who lowered their A1C by four percentage points in the first six months reduced their overall risk by 20 percent compared with those whose A1C did not go down. A drop of two percentage points, in comparison, reduced the overall risk by 8 percent.


An A1C below 6.5 percent may offer people newly diagnosed with type 2 diabetes the best protection against heart attack, stroke, and early death, As A1C levels rise, so does risk. Dramatic early drops in A1C levels also contribute to better protection, so the faster you get your blood glucose under control after diagnosis, the better your long-term health may be. However, such stringent control is not recommended for everyone. The study authors point out that the participants who achieved such control may have had a low risk of hypoglycemia (low blood glucose). And keep in mind, improved blood glucose control benefits your health, even if you've lived with diabetes a long time.

Early Glycemic Control and Magnitude of HbA1c Reduction Predict Cardiovascular Events and Mortality: Population-Based Cohort Study of 24,752 Metformin Initiators.” Elisabeth Svensson, Lisbeth M. Baggesen, Søren P. Johnsen, Lars Pedersen,1 Helene Nørrelund, Esben S. Buhl, Christiane L. Haase, and Reimar W. Thomsen. Diabetes Care, June 2017; 40: 800–807.

The information on this screen does not take the place of care from your doctor or other health care provider. If you have general questions about diabetes or diabetes-related research, e-mail askada@diabetes.org or call 1-800-DIABETES (800-342-2382).



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