The diabetic hemoglobin A1C test is a fairly new way to measure glucose levels in the blood. It was developed when researchers discovered the glycation process, and in 1986 the testing program was launched into the medical community.
It caught on fast because it is a wonderful way to know a patient's blood sugar level rates over the last couple of months. And there was hope that giving diabetics a simple number to shoot for would encourage better blood sugar control.
Because it is so new, researchers are still doing tests to find proof that lower fractions (measured as percentages) in diabetics will also lower the risk for diabetic complications over many years. Most non-diabetics test in the range of about 4% to 6%. A type 2 diabetic can test 10% or higher if blood sugars are not being controlled.
And studies are showing that at levels higher than 8% the complications are going to multiply and get worse as the years pass by. This is a huge problem. The National Institute of Health says the estimate of type 2 diabetics with poor blood sugar control in the US is 40-60%. They see the diabetic hemoglobin A1C as a powerful tool to change this.
Diabetic Hemoglobin A1C Testing
As a type 2 diabetic I get the HbA1C test every three months. That's because I'm on insulin. If you are on oral medicines or just diet and exercise to control your blood sugars you probably only get the test twice a year.
And doctors are seeing that consistent readings of 6.5% or lower have been keeping the heart, kidney, retinal and peripheral complications from becoming life-threatening in type 1 and type 2 diabetes. Lower diabetic hemoglobin A1C does equal lower risk of complications.
The reason? If your HbA1C is lower, it means you have fewer AGEs, advanced glycation end products, in your blood and therefore in your organs, including your brain, heart, blood vessels and eyes. The test is simply telling you how well you are keeping them out of your system.
What the Diabetic Hemoglobin A1C Is Not Telling You
Diabetic medications cause hypoglycemia to some degree, and insulin does this more than the oral medicines. You are trying to control the amount of blood sugar in your body by artificial means. Your body's defenses against a blood sugar that is too high or too low are delicate and complicated. Meds can not duplicate it.
Minute by minute your endocrine system uses its arsenal of hormones to regulate your blood sugar so it does not go too low. When it senses a dip to 70 it releases epinephrine, you feel nervous, and your heart starts pounding.
Hormones tell your liver to release some of the sugar stored there over the next few hours, and they restrict the amount of glucose available to your hands and feet. If these measures do not stop the lowering of blood sugar you start having neurologic symptoms, blurred eyesight, profuse sweating and sleepiness.
And the more often that low blood sugar events happen, the less sensitive you become to the onset of hypoglycemia. The diabetic hemoglobin A1C can not tell you or your doctor how often this is coming to you.
Hypoglycemia at night can go unnoticed if it happens a lot. It may be a cause of the dawn phenomenon, when you wake up with a much higher blood sugar than you measured the night before. Sensing a low blood sugar, your liver released sugar to raise it, and since you have diabetes, insulin did not respond as it would in a non-diabetic.
There are significant risks to having many hypoglycemic episodes. The first is that you become less sensitive to them, and if you do not have early warnings your sugars may dip dangerously low before you are aware of it.
Hypoglycemic attacks take a toll on a diabetic heart in the long run. So older diabetics are the ones who are showing the results. Only constant blood sugar monitoring can tell you how much low blood sugars are occurring. The diabetic hemoglobin A1C can not warn you of a hypoglycemic attack.
The Case for Not Having the Same HbA1C Target for Every Diabetic
Studies performed over several years in older diabetics are showing some surprises. They are proving that diabetic hemoglobin A1C over 7.5% to 8% does go along with higher death rates from complications.
They also show higher death rates if the HbA1C is kept at less than 6.5%. This is especially true if older diabetics have heart failure or nephropathy, what doctors call comorbidities (having two or more conditions that can cause death).
As diabetics are living longer, doctors who study and work with this aging population are learning that the optimal ranges for things like BMI, blood pressure and diabetic hemoglobin A1C need to be different from those for younger, newer diabetics.
They say that for type 2 diabetics with a history of heart failure it is best to keep the HbA1C between 7% and 7.8%, and for those with kidney disease this also seems optimal. There is no benefit in trying to lower blood sugar beyond that.
In fact, pushing for lower numbers raises the statistics for death as much as having high blood sugar. These studies are so new that the cause has not been figured out yet. But doctors who treat older patients think the problem may be a higher number of hypoglycemic attacks. They are caused by trying tighter blood sugar control using medicines.
Applying the same rules about good ranges in older patients as in youngger ones is a big mistake. Elderly patients with a slightly higher BMI than fits the standards survive heart attacks and other illnesses better than thin patients.
Not treating cholesterol and blood pressure with medication as aggressively in older patients is turning out to be a good idea. And the same is true for blood sugar. In aging diabetics there are smaller benefits from tight blood sugar control.
Measured against the catastrophic results of hypoglycemia, a diabetic hemoglobin A1C of 6.5% or lower is just not worthwhile. But that is only for long-term diabetics with a high risk for cardiovascular disease, who have heart failure or kidney disease.
Those who have a diabetic hemoglobin A1C below 7% by diet and exercise do not face the same risks and usually do not have those other problems either. And there is no doubt that the closer the HbA1C is to the non-diabetic 6% level, the lower the likelihood of diabetic complications in your eyes, heart, kidneys and feet.
New diabetics need to try for the 6.5% diabetic hemoglobin A1C. And all of us with type 2 diabetes need to do our best to lower our blood sugar naturally with a sensible diet that leaves out the AGEs, and we need exercise for weight loss and cardiovascular health.
Insulin and oral medications are necessary, but the less we have to depend on them with type 2 diabetes, the better we will do as we age. It's exercise and eating healthy food that will improve the quality of our years as we live longer and longer with chronic conditions like diabetes.
Whatever you decide to do, "be happy in the life you have chosen." (Charles Dickens).