Dr. Roach: Goal-setting for diabetics: What is a ‘normal’ glucose level?

Keith Roach
To Your Health

Dear Dr. Roach: All my friends who are hypertensive have been able to bring their blood pressure to 120/80 or less. However, I have diabetic friends who are taking several diabetic drugs but none has been able to bring the fasting glucose levels to the ideal amount, around 85. As a matter of fact, none is even near 100. Is this situation common? Why is it so hard to lower the fasting glucose levels?

— R.I.

Dear R.I.: The “ideal” level for neither blood pressure nor blood sugar is known for certain across all age groups and risk levels. The consensus opinion for the best goal has changed over time, depends on a person’s situation, and isn’t even agreed upon by all experts.

However, there is indeed increasing evidence that blood pressure, at least for people at higher risk for heart disease, should be in the low range of 120/80. The medications we have now are very effective at getting the blood pressure down, with a low risk of side effects, for most people, even if without a very healthy lifestyle, including diet, exercise and stress.

Diabetes control can be measured by fasting glucose, but a better predictor of diabetes complications is the hemoglobin A1C. It is affected by both fasting and non-fasting glucose, and looks at overall blood sugars over the preceding weeks to months. Some people have low fasting sugars but extremely high sugars after eating.

The A1C level in a person without diabetes is normally between 4% and 5.6%. That’s an AVERAGE (not fasting) blood sugar of 70 to 126 mg/dL. However, it’s not recommended for most older Type 2 diabetics to have an A1C level that low. Part of the reason is that people with an A1C that low are at risk for having so low a blood glucose that they can develop symptoms of hypoglycemia. Extremely low blood sugars are very dangerous for a person taking diabetes medication.

Another part of the reason that many people with diabetes are recommended an A1C level closer to 7% (an average glucose level of less than 154 mg/dL) is the result of the ACCORD study. It showed that people with diabetes who are at high risk for heart disease were more likely to suffer a heart attack if striving for more stringent blood sugar goals. So, the idea that there is an ideal fasting blood sugar goal is oversimplified; 85 will be wrong for many, but 80-130 is a range most will fit into.

Some people with diabetes, especially younger people or those with Type 1 diabetes, may be recommended to have a near-normal A1C. Very tight control reduces the risks of developing certain complications, especially of the eyes, nerves and kidneys.

So, part of the reason your friends don’t have a near-normal blood sugar is that they have been told that isn’t the right goal for them. Those who do have a goal of tight control need to be meticulous about their diet, their exercise and their medication in order to achieve a near-normal A1C without risk of low blood glucose.

It’s not easy and requires coordinated effort, not just by the patient, but also by the health care team, which may include physicians, registered dietitians and nurses. Newer treatments and diagnostics, such as insulin pumps, more medication options and continuous glucose monitors, have made the goal more possible to obtain for people with hard-to-control diabetes, but is still very difficult for some.

Many people with Type 2 diabetes will have a much easier time getting blood sugars near normal with weight loss, especially if they lose weight early in the course of the disease.

Readers may email questions to ToYourGoodHealth@med.cornell.edu.