Blood glucose monitoring tools: Putting them all together
Q: With the tools available now to monitor blood sugar that help to keep numbers as normal as possible, is there more potential for hypoglycemic reactions?
A: Most people with diabetes strive to achieve blood glucose levels within a specified target range that’s closest to normal physiologic levels. In my experience, too many people have set unrealistic, low targets, believing lower (often too low) is better because of fear of complications from high blood glucose levels.
Unfortunately, this mind set of low is better, can often lead to overtreatment and frequent hypoglycemia, which must be avoided if we want to help preserve hypoglycemia signs and symptoms. Glucose monitoring tools have the ability to both help and hinder.
The three tools that determine the level of glucose control are a blood glucose meter, glycated hemoglobin (HbA1c) test result and a continuous glucose monitor (CGM). Looking at these tools collectively will provide you and your healthcare team with the most complete glucose picture.
A blood glucose meter provides the most accurate (excluding user error) real-time blood glucose level by providing you with an immediate capillary glucose result. It is this capillary result that we ask you to use for insulin determination in hyperglycemia and treatment with glucose for hypoglycemia. We generally recommend 4-6 blood glucose checks per day to optimize control, providing 4-6 photo snapshots of the blood glucose levels. Even with this incredible commitment to self-management, information regarding blood glucose levels between these readings is unknown.
The elusive 6-7 percent HbA1c is, for me, an over-rated determinant of glucose control. Your 3 monthly HbA1c result provides you with an average of your glucose control over the previous 2-3 months. Many people strive for years to obtain the elusive 6-7 percent HbA1c result, only to find when they do achieve it, the healthcare team may still want more.
To explain my point, in a recent Mastering Your Diabetes Program, those participants who did have their HbA1c under 7 percent, demonstrated the greatest swings in blood glucose levels from hypoglycemia to hyperglycemia. Remember, an average blood glucose level of 120mg/dL (the midpoint of 80-160mg/dL), would equate with an HbA1c result of 6 percent and who wouldn’t be happy with that – right? But you can also achieve the same HbA1c with blood glucose levels ranging from 30-210mg/dL – riding the diabetes rollercoaster. An HbA1c result must be assessed in conjunction with capillary and / or CGM data to identify its true value.
Our third tool, CGM, in essence, provides a DVD of the individual’s glucose control. Although invaluable in providing data regarding glucose trends, CGM can lead to reactive management when you are receiving up to 288 glucose readings every 24 hours – information overload! Hypoglycemia, from over-correction, is a significant education point. We must remember that because CGM measures interstitial fluid glucose levels, there can be up to a 20 percent variability compared to capillary glucose readings and sometimes more when the glucose level is changing rapidly. Confirmation of data with a capillary reading is essential for accuracy and takes priority.
In essence, each glucose-monitoring tool has value, but true value comes from collective review.