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Teaching Patients About Glycemic Variability and Why It’s Important

Laurel Fuqua, RN, MSN, CMC

Under normal circumstances, blood glucose levels vary throughout the day. While it may not be of much significance to a healthy subject, the degree of these changes is of great importance to individuals with diabetes.

Health care professionals (HCP) know that the first step for any person to live a full life, even with diabetes, or any other health condition, is to have enough knowledge about the disease. In diabetes, understanding blood glucose behavior will help patients adjust their lifestyle and engage more with their treatment plan. This will help them avoid current and future problems associated with diabetes complications.

However, before addressing blood glucose behavior, it is important that patients understand some key terminology. Variability is often a hard concept for patients to grasp. Below are patient focused definitions that might help.

  • Glycemia means glucose (sugar) in the blood. Glycemic therefore means ‘in relation to blood sugar in the blood.’
  • Variability means changes from one level to another. In reference to blood sugar, it means the way blood sugar levels change from one value to another, especially how high or how low it goes in a given period of time.

So glycemic variability (GV) means: the changes (swings) that take place in the amount of glucose (sugar) in the blood and over a given period of time.

Helping patients understand why they should pay attention to glycemic variability
There are many reasons why it is important to teach patients to pay attention to glycemic variability, some obvious and some not so obvious.

The most obvious reason for patients is that it doesn’t feel good to have their blood glucose always swinging up and down. Nobody wants to be chasing his or her blood sugars all day long trying to keep it in range. Life with diabetes is stressful enough. Another obvious reason is that the more the person’s blood sugars are swinging up and down, the more likely it is that they have dangerous highs and lows. Some of these, if not caught soon enough, could result in serious medical complications like severe hypoglycemia or diabetic ketoacidosis.

There is clinical data showing that people with high blood glucose variation are at a higher risk of having hypoglycemia or even severe hypoglycemia than those with low glycemic variation. [1] Glucose variability has been shown to be independently predictive of severe hypoglycemia in type 1 diabetes [2] and also predictive of nonsevere hypoglycemia in type 2 diabetes [3].

Less obvious is the fact that getting the patient’s A1C under control in intrinsically tied to their glycemic variability. For someone with high variability, reducing A1C is much harder because with more blood sugar swings they may tend to have more of a risk of hypoglycemia.

So if they take more insulin, or take other diabetes management actions to improve A1C, they could increase the risk of severe hypoglycemia by deepening the swings to the low end of the range. That’s why if one wants to reduce a patient’s A1C and their variability is high, it is important to pay particular attention in reducing their variability at the same time.

And it’s important for patients to know that they can have a normal or moderate A1C value and still have high glycemic variability. By only looking at the patient’s A1C number the HCP could be missing this, and not realize that the patient is at real risk of some dangerous glucose swings that could be averted if glycemic variability was reduced.

And if that’s not enough, experimental findings and some pre-clinical studies have suggested that glycemic variability induces oxidative stress, which provides a positive indication that glucose variability may be involved in the development of vascular disease. [4] There is still no definitive study tying glucose variability to long term complications, but it’s possible that glycemic variability could be causing both short term complications and long term complications as well. [5]

How to measure and track glycemic variability
There is a lot of debate about the best way to track glycemic variability. The author has offered thoughts below on a tool that she believes has advantages, but what is most important is that health care providers help patients track it in some way using some type of glycemic variation “report card.” Most importantly, use a tool that both the patient and health care providers are comfortable with.

Some of the more common tools available use the simple Standard Deviation or Interquartile Range. However these tools were not designed with the diabetes patient in mind. As a result, these tools may be better at measuring swings to the high end, but not necessarily the low end.
Scientists at the University of Virginia designed another tool, however, called the Average Daily Risk Range (ADRR), specifically for diabetes patients. It takes into account how people test, and the relative clinical risk of going low versus going high. In fact, a study published in Diabetes Care showed it is a more balanced predictor of both high and low blood glucose swings than other measures of variability like Standard Deviation and Interquartile Range. It is also very sensitive to deep lows and significant highs, because they present much more clinical risk for the individual with diabetes.[6]

ADRR has been characterized in large number of diabetes patients, so it is known what numbers are “high” or “low”. An ADRR number above 40, for example, is considered “high,” and was associated with patients having, on average, more than half of their readings below 70 mg/dL or above 180 mg/dL in the subsequent month. [7]

ADRR is an important tool that could help people understand not only their glycemic variability, but also their risk of short term complications. But again, what’s most important is that health care professionals and patients use SOME kind of tool for tracking glycemic variability.

How to help patients maintain a low glycemic variation
Once a way to measure and track glycemic variability has been selected, the next step is to figure out ways to reduce variation and keep it as low as possible. First the HCP will want to teach the patient how to determine if the variability is caused by a swing predominantly towards one end of the glucose range. For example, the glucose swings may be predominantly towards the high end of the range only, and the patient may not be having much hyperglycemia. If the patient is mainly just skewed high, it may be that the HCP will need to work with them to see if a more intense treatment regimen is appropriate. If their variability is only skewed to the low end, the HCP may actually want to consider a less intense treatment regimen.

There are also options available today that help inform the HCP and patients of daily patterns of highs, lows or swings during certain times of the day (i.e. in the morning or evening) that could be increasing glycemic variability, no matter whether the swings are towards one end of the scale or all over the place. If these daily patterns are corrected, their glycemic variability may decrease over time.

Conclusion
In summary, helping patients understand glycemic variability and the daily patterns of their blood glucose readings are important for their diabetes control. ADRR is one glycemic variability measure that, when used in conjunction with A1C, can help determine where a patient’s blood sugars are heading. Today, there are easy to use technology and other tools available that can help with understanding and managing glycemic variability.

References:

  1. Cox DJ, Kovatchev BP, Julian DM, et al. Frequency of severe hypoglycemia in insulin-dependent diabetes mellitus can be predicted from self-monitoring blood glucose data. J Clin Endocrinol Metab 1994;79: 1659–1662
  2. Kilpatrick ES, Rigby AS, Goode K, Atkin SL. Relating mean blood glucose and glucose variability to the risk of multiple episodes of hypoglycaemia in type 1 diabetes. Diabetologia 2007;50:2553–2561
  3. Qu Y, Jacober SJ, Zhang Q, Wolka LL, DeVries JH. Rate of hypoglycemia in insulin-treated patients with type 2 diabetes can be predicted from glycemic variability data. Diabetes Technol Ther 2012;14:1008–1012
  4. Monnier L, Mas E, Ginet C, Michel F, Villon L, Cristol JP, Colette C. Activation of oxidative stress by acute glucose fluctuations compared with sustained chronic hyperglycemia in patients with type 2 diabetes. JAMA 2006; 295: 1681-1687
  5. Standl E, Schnell O, Ceriello A. Postprandial hyperglycemia and glycemic variability: should we care? Diabetes Care 2011; 34 Suppl 2:S120-7.
  6. Kovatchev BP, Otto E, Cox D, Gonder-Frederick L, Clarke W. Evaluation of a new measure of blood glucose variability in diabetes. Diabetes Care 2006; 29: 2433-2438
  7. Patton SR, Clements MA. Average daily risk range as a measure for clinical research and routine care. J Diabetes Sci Technol 2013; 7: 1370-1375