Explaining Your Diabetes Numbers: HbA1C

When I was first diagnosed with diabetes, my nurse educator introduced me to the "diabetic truth detector," HbA1C. Glycosylated hemoglobin, or hemoglobin A1C, she insisted, would give my doctor the truth behind my blood sugar readings in a test it was impossible to fake.

Actually, it's impossible to fake the everyday blood glucose readings diabetics need to take first thing in the morning and after every meal, too, but HbA1C is a measure of long-term blood sugar control. What most doctors don't tell diabetics is that it is very easy to manipulate HbA1C through healthy habits.

What Is Glycosylated Hemoglobin?

Glycosylated (or glycated) hemoglobin is a small fraction of the body's oxygen-carrying hemoglobin protein that is chemically bound to glucose. During their 90-day life span, some red blood cells are exposed to enough sugar as they circulate in the bloodstream that a certain amount of glucose "sticks." The higher the average glucose level in the bloodstream, the higher the percentage of red blood cells that contain glycosylated hemoglobin. Everyone has at least a small percentage of HbA1C, although diabetics may have 7 percent, 10 percent, 20 percent, or even more. Acceptable diabetic control usually results in a 6 percent to 7.5 percent HbA1C range, while a HbA1C normal range (some doctors urge their diabetic patients to strive for 7 percent), for non-diabetics, is more on the lines of 4.5 to 5 percent.

While blood glucose levels go up and down constantly, even in healthy people, HbA1C levels are not affected by hour-to-hour changes in diabetic control. HbA1C percentages change over the entire life span of the red blood cell, which is the reason doctors test HbA1C about once every 90 days. 

Understanding Surprises in HbA1C Readings

When diabetics get HbA1C readings that don't line up with the blood sugar readings they take at home, they usually are taking fasting blood sugar levels but skipping post-prandial (after-meal) readings. Especially in the early stages of type 2 diabetes, the insulin-making beta-cells of the pancreas may retain the ability to lower blood sugar concentrations back down to normal overnight. They may lack the ability to "unpack" stored insulin to normalize blood sugar levels quickly after meals. Taking a fasting blood sugar level every morning may give the impression that diabetes is under good control, when in fact high glucose levels for hours after meals are increasing the underlying problem, insulin resistance, and increasing the risk of complications.

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Any time blood sugar levels exceed about 170 mg/dl (9.4 mmol/L), insulin resistance increases. Cells in the skeletal muscles and liver shut down receptors for insulin to protect themselves from receiving too much glucose. In the early stages of type 2 diabetes, the pancreas responds by pumping out more insulin, whereupon muscle and liver cells shut down still more insulin receptors to become even more insulin resistant. High levels of insulin in the bloodstream deactivate an enzyme essential for releasing fat from fat cells to be burned elsewhere in the body, so it becomes harder and harder to avoid weight gain. Glycated proteins on nerve cells can spur peripheral neuropathy, retinopathy, and even foot infections (as nerves to the sweat glands fail to keep the skin moist, and cracks in the skin admit infection). All of this can happen to people who think, on the basis of taking just one blood sugar reading every morning, that their diabetes is in good control.

Healthy Choices That Lower HbA1C

By far the most important change diabetics can make when their HbA1C numbers are too high is simply to start testing after meals as well as first thing in the morning. If blood glucose levels jump to 250 mg/dl, 300 mg/dl, or more (13.9 mmol/L, 16.7 mmol/L, or more) it is imperative to make changes to diet and/or medication. Any blood glucose reading of 170 mg/dl (9.4 mmol/L) at any time indicates a need for a change to prevent insulin resistance. Even type 1, insulin-dependent diabetics can develop insulin resistance when their blood sugar levels run too high after meals. However, sometimes changes that get blood sugar levels and HbA1C levels aren't as onerous as diabetics fear.

• Eating too great a volume of food, not just too many carbohydrates, can cause blood sugar levels to soar. If you were to eat a whole head of lettuce for lunch, for example, you would still not consume a lot of carbohydrate, but you might have a blood sugar reading well over 300 mg/dl (16.7 mmol/L). That's because the lining of the small intestine senses large volumes of food, and sends a signal to the pancreas to release (1) insulin to control blood sugar levels and (2) glucagon to increase blood sugar levels just in case the large volume of digested food doesn't contain a lot of carbohydrate. Diabetics don't release insulin very well, but they still release glucagon. The glucagon stimulates gluconeogenesis, the release of glucose from glycogen stored in the liver. This can make blood sugar levels soar even without a high-carb, sugary meal.

• It's harder to recover from "pigging out" than from modest overindulgence. If your body needs 10 units of insulin to bring blood sugar levels down from 200 mg/dl to 150 mg/dl, it might need 20 units of insulin to bring blood sugar levels down from 300 mg/dl to 250 mg/dl. Your body exerts exponentially more effort to recover from a whole pie than it expends to recover from a piece of pie. Keep any excursions from healthy diet small, and measure your blood sugars even when you know they will be high, so you will be better prepared to avoid dietary choices that make the situation even worse.
• Good mitochondrial health mitigates the effects of diabetes. Part of good mitochrondrial health is consuming a variety of natural antioxidants. Diabetics actually need salads and, in small amounts, even fruit. R-lipoic acid, biotin, and L-carnitine supplements increase the efficiency of sugar burning in mitochondria and lower both post-prandial blood sugar levels and HbA1C.

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There are some bad choices that also lower HbA1C levels. Methamphetamine addicts, for example, have notoriously low HbA1C levels despite craving sugar all the time, as low as 1-2 percent HbA1C (which would be physiologically impossible without the illegal drug). People who lose large amounts of blood in accidents have temporarily lower HbA1C levels, as do people who have diseases that break down red blood cells.

Healthy decreases in HbA1C, however, result from healthy choices. Never stuff yourself. Save part of a special treat for later. Most importantly, test every morning and after every meal.