A1C — Your Blood Sugar Average for the Last Couple of Months


By Wil Dubois

A super-quick review for those of you who snuck into this article form the back door: we dFolk are bombarded with numbers, goals, and targets. We're frequently told where we should be, but not how high our risk is when we can't reach our targets. In this series of discussions we look at all of our important numbers and break them down into a simple green light, yellow light, red light format to put all of your critical numbers into a useful context. To give you perspective on when and how much to worry. When to relax, when to call your doc, and when to call 911.

Green light A1C score

The target for A1C, the green light, is between 6.0% and 6.9%. These numbers are commonly expressed simply as 6.0 and 6.9, without the "%" sign. If your A1C falls into this zone, you're considered to be in control. For perspective, these numbers can be converted into "meter" numbers, called estimated average glucose — eAG for short. The green light eAG range is 126 mg/dL (7 mmol/l) to 151 mg/dL (8.39 mmol/l). But what if your numbers are higher than target? Or lower than target? When are you actually in danger?

Yellow light A1C score

If the light turns yellow as you approach the intersection, you need to either speed up or stop. Whichever is safe under the circumstances, right? If your A1C is between 7.0 and 8.9 you'll be classified as "out of control." But how much danger are you in? Frankly, it depends on how close you are to either end of the spectrum. Yellow light A1Cs are higher than is strictly healthy, but pose no immediate harm. However, the higher you are in this range, the closer you are to a red light; and we'll talk about just how serious that can be in a minute.

I should point out that there are some special cases. If you're a very young type 1, a yellow light A1C score may be considered in target for you until you get older. Similarly, if you're an elderly type 2, you doctor may choose to "green light" you in the yellow zone. Don't worry, it's not the same as being "gaslighted."

You're also in yellow light territory if you use insulin or pills called sulfonylureas and your A1C is below six. Numbers in the low fives and below are considered non-diabetic, so at first glance they might seem like an attractive place to be. The better controlled, the better, right? Uh. Wrong. Sorry.

The simple fact of the matter is that if you have an A1C below six, it means you're having low blood sugars, and lows are every bit as dangerous as highs. If too much medication is forcing you below 6.0, you're staring at a yellow light. Put on the brakes.

Red light A1C score

An A1C score above 9.0 is considered "critical" high. Red light. Danger. But why? At an A1C of 9.0 (eAG 212 mg/dL, 11.78 mmol/l) your blood sugar is high enough to begin the slow process of destroying your kidneys and your eyes; to light the fire of neuropathy. It's cytotoxic, meaning lethal to cells. Or, as one dialysis nurse I know likes to say: "It's incompatible with human life."

You shouldn't panic if your A1C is this high. Most people are above 9.0 when they're diagnosed. But it's a red light. Stop. In this case, back up and go the other direction. A high A1C for brand-new diabetes is just a problem that needs to be fixed. Often minor changes in lifestyle and/or some meds will whip it into shape in no time. On the other hand, if you've been lower than 9.0 for a long time, and have now crossed the red-light Rubicon, it tells us your diabetes has advanced beyond your therapy. This is no fault of your own. It's what diabetes does. It changes. It advances. No guilt. But you do need to stay one step ahead of it. You'll need a change of therapy.


The A1C green light score is between 6.0% and 6.9%.

The A1C yellow light score is between 7.0% and 8.9% on the high end, or below 5.9% on the low end.

The A1C red light score is more than 9.0%


Read Diabetes by the Numbers in full.

Last Modified Date: June 14, 2013

All content on dLife.com is created and reviewed in compliance with our editorial policy.

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