Whether you’re new to diabetes or have had it for a long time, you likely know that the “gold standard” of assessing the level of your diabetes control is determined by an A1C measurement. In fact, it’s pretty hard to not hear about the importance of knowing your A1C as a marker of the state of your diabetes. There’s no doubt that the A1C is at the top of the list, but does it tell the whole story? Are there other ways to assess how your diabetes is really doing?
An A1C primer
The A1C, sometimes called HbA1C, hemoglobin A1C, or glycosylated hemoglobin, is the standard for measuring blood sugar control in people who have prediabetes or diabetes. Why? Well, it’s a reflection of your average blood sugar levels over the past three months. If you’re checking your blood sugars with a meter (and hopefully you are!), you’re getting an indication of what your blood sugar is at a particular moment in time, say, 8:30 in the evening. But, because blood sugars aren’t static — they go up and down throughout the day and night, you don’t know what’s happening at other times of the day. That’s where the A1C comes in.
Why is knowing your A1C so important, anyway? Two landmark studies — the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) — tell us that the higher the A1C level, the higher the risk of certain diabetes complications, such as eye, nerve, and kidney disease. The general A1C goal for most adults who have diabetes is less than 7 percent, although it’s important to realize that your goal may be different. National diabetes care guidelines recommend getting your A1C checked at least twice a year, or more often if your A1C is not at goal.
The A1C is often put on a pedestal as the sole indicator of how someone’s diabetes is doing. But while the A1C deserves its share of kudos for showing you and your doctor how your diabetes treatment plan is working out, it’s far from perfect. In fact, not checking your blood sugars and solely relying on your A1C to tell the whole story can give you a false sense of security and be downright misleading. This has to do with something called “glycemic variability.” Here’s a run-down of what glycemic variability means:
• Glycemic variability (sometimes called glycemic excursions) refers to swings, or ups and downs in blood sugar levels over a given period of time.
• Blood sugar ups and downs, or highs and lows as they’re referred to in the diabetes world, can be hard to manage. It can feel like you’re spending all day trying to chase blood sugars, and who has time for that?
• Along with the time-consuming task of trying to rein in your blood sugars, you have to deal with the fact that having frequent high and low blood sugars can leave you feeling poorly, physically, mentally, and emotionally.
• Research shows that people who have a high level of glycemic variability have a higher risk of severe hypoglycemia (low blood sugar).
• One can have a “good” A1C level and still have high glycemic variability.
Remember that the A1C is an average. It doesn’t tell you or your doctor how often your blood sugar has been high or low. In fact, it doesn’t reflect hypoglycemia at all. In short, it doesn’t indicate the amount of glycemic variability that you’ve been having. To illustrate this, let’s look at two people with an A1C of 7 percent:
• Person A’s blood sugars have been in range close to 100% of the time over the last three months.
• Person B’s blood sugars have been in range only 20% of the time over the past three months; the rest of the time, blood sugars have been high or low.
If one only looks at A1C, then, Person B is in a bit of a tough place, as he or she is at risk for short-term complications (highs and lows, potentially severe), as well as long-term complications, such as heart or eye disease. The A1C doesn’t pick up on the lows or highs.
Going beyond A1C
How else can you and your health-care team truly assess the state of your diabetes? It’s important to note that the A1C measure is still key. Don’t give up on it. But look beyond it, especially if you are at risk for hypoglycemia. You’re at risk if you take insulin and/or if you take a class of diabetes pills called sulfonylureas (e.g., glipizide, glyburide and glimepiride) or meglitinides (such as nateglinide [brand name Starlix] and repaglinide [Prandin]).
There are research algorithms that can help your doctor determine the extent of glycemic variability. One such algorithm is the Average Daily Risk Range (ADRR). However, this is a rather complex calculation and not very practical for day to day use. Other, less arduous options include:
The fructosamine test can detect blood sugar changes within a few weeks, rather than months. It indicates the level of blood glucose control over the past two to three weeks.
A relatively new technology, CGM provides measures of glucose every 5 to 15 minutes, and is one of the best ways to scout out glycemic variability. However, CGM can be pricey, and most insurance plans cover this only for those with Type 1 diabetes and possibly, those with Type 2 diabetes on multiple injections of insulin. Hopefully, the tide is changing on this, as CGM has been shown to improve glycemic control in both Type 1 and Type 2 populations. You may also have the option of using a professional CGM device, whereby you wear a device owned by your health-care provider for up to six days. You then return the device, and the data is downloaded and analyzed by your provider. Professional CGM does not require the purchase of a CGM device. Dexcom, Medtronic, and Abbott all have professional CGM devices.
Switching up your blood sugar checks
Self-monitoring of blood glucose (SMBG) is an important part of managing your diabetes. If your A1C isn’t at your target, or, if your A1C is at target but you’re having frequent symptoms of high and low blood sugars, check your blood sugars a) more often than usual and b) at different times of the day. If you only check your blood sugar in the morning, for example, you won’t know what’s happening at other times of the day, so you won’t pick up on any glycemic variability. Understandably, test strips are expensive, so if cost is a limiting factor, you might pick a few days out of the month to check your blood sugar before each meal and at bedtime. Or, you could vary the time you check each day — one day, check before breakfast, the next day, check before lunch, and so on. Don’t forget to occasionally check two hours after your meals, as well as after you exercise.
Keep track of your blood sugars
Download your meter readings and look them over. Or, use a logbook or a smartphone app to track your blood sugars. Look for patterns of highs and lows and think about what may be causing them. Share your results with your health-care team.