Blood Glucose Self-Monitoring: Smart Monitoring

The History and Future of Blood Glucose Monitoring[1]

If you checked your blood glucose level two hours after lunch, and it clocked in at 287 mg/dl, what could you tell me about the effect of your lunch on your glucose level?

Absolutely nothing.

You don’t know anything about the effect of the meal because you don’t know what your blood glucose level was before the meal. Sure, most people would agree that 287 mg/dl is above target for an after-meal glucose reading, but this single number by itself is highly uninformative. It has no context. If your glucose reading had been 114 mg/dl before the meal, then of course you would know that either your choice of foods or your mealtime diabetes treatment is in serious need of adjustment.

But what if you were at 250 mg/dl before lunch? In that case, your blood glucose level rose by only 37 “points.” There was nothing wrong with the meal. Sure, there’s a problem that needs to be fixed, but it has nothing to do with lunch.

As this example demonstrates, isolated blood glucose checks are next to meaningless; they don’t tell you anything about how you got to where you are. “Smart” monitoring, on the other hand, does, because it follows a pattern. And the most basic pattern is monitoring before and after an event or activity.


What is type 1 diabetes?

Type 1 diabetes is an autoimmune disorder in which the immune system attacks and destroys the insulin[2]-producing beta cells[3] in the pancreas. As a result, the pancreas produces little or no insulin. Type 1 diabetes is also characterized by the presence of certain autoantibodies against insulin or other components of the insulin-producing system such as glutamic acid decarboxylase (GAD), tyrosine phosphatase, and/or islet cells.

When the body does not have enough insulin to use the glucose that is in the bloodstream for fuel, it begins breaking down fat reserves for energy. However, the breakdown of fat creates acidic by-products called ketones[4], which accumulate in the blood. If enough ketones accumulate in the blood, they can cause a potentially life-threatening chemical imbalance known as ketoacidosis.

Type 1 diabetes often develops in children, although it can occur at any age. Symptoms include unusual thirst, a need to urinate frequently, unexplained weight loss, blurry vision, and a feeling of being tired constantly. Such symptoms tend to be acute.

Diabetes is diagnosed in one of three ways – a fasting plasma glucose test[5], an oral glucose tolerance test[6], or a random plasma glucose test – all of which involve drawing blood to measure the amount of glucose in it.

Type 1 diabetes requires insulin treatment for survival. Treatment may also include taking other drugs to prevent kidney damage[7] or to treat diabetes-related conditions such as high blood pressure[8].


Testing in pairs

The term “testing in pairs” was coined by Dr. Bill Polonsky of the Behavioral Diabetes Institute in San Diego. A pair is a set of blood glucose readings taken at bedtime and the next morning, before and after a meal, or before and after exercise, to give a few examples. By monitoring in pairs, each number gives context to the other. Instead of two meaningless data points, the two readings work together to tell a story.

Bedtime and morning readings mainly tell you the story of what happened in your sleep. Did your blood glucose rise between bedtime and morning? If so, it is likely that your liver is dumping excess glucose into your system while you sleep. (Other possibilities include the Somogyi effect[9], in which the body responds to low blood glucose by raising it, and the dawn phenomenon[10], in which the body releases certain hormones in the early morning that cause the blood glucose level to rise.) Your doctor can fix nighttime problems by adjusting your insulin regimen — but not if he or she doesn’t know about them. If you don’t monitor and then report your results, any problems are likely to go unresolved.

Monitoring around meals tells two different stories: First, your reading before a meal is a reflection of the period leading up to the meal. If your glucose level is above target before a meal, your basal, or baseline, therapy for your fasting state might need to be adjusted; or the previous meal may have thrown you out of whack. Second, the change between your premeal reading and its postmeal partner in the pair is the measure by which you can judge the impact of the meal and how successfully the meal and your therapy are matched to each other.

The only situation in which an isolated blood glucose reading has value is to either confirm or rule out hypoglycemia[11] (low blood glucose). If you feel “low,” you should check with your meter to confirm that what you’re feeling is real and to determine how dangerous your situation is. But even in this circumstance, a pair has value: After treating your hypoglycemia, you should check your blood glucose again to ensure that the crisis has been averted and to judge how effective your intervention was. If your blood glucose level shoots up later in the day, you probably overtreated the hypoglycemia, and this is good information to have for your next low.

How often should you check?

How many pairs of blood glucose checks you deploy in a day likely has more to do with your health insurance coverage than with your specific health situation — and it may be fewer than you ideally “should” do. Insurance plans are notoriously stingy when it comes to covering blood glucose test strips, a position that is based on a wrong interpretation of medical guidelines.

For a number of years, the standards of care for diabetes from the American Diabetes Association (ADA), which are the guidelines under which most people in the United States receive treatment (other specialty medical associations, such as the American Association of Clinical Endocrinologists [AACE], offer competing guidelines), stated that people taking only oral drugs should monitor at least once a day, and that those taking insulin should monitor at least three times a day. Somehow, both the Centers for Medicare and Medicaid Services (CMS), and then commercial health insurance plans, latched onto this guideline while ignoring the “at least” part of each sentence. So for many years, the default number of strips covered by insurance was a woefully sparse one or three per day, depending on a person’s type of therapy. True, most doctors could eke some more strips out of health plans, but it was a bit like wringing water from a stone, and it took a lot of unreimbursed time and paperwork to make it happen.

In January 2013, however, the ADA strongly clarified its intent, saying that anyone who uses an insulin pump[12] or takes multiple daily insulin injections “should do SMBG [self-monitoring of blood glucose] at least prior to meals and snacks, occasionally postprandially [after meals], at bedtime, prior to exercise, when they suspect low blood glucose, after treating low blood glucose until they are normoglycemic, and prior to critical tasks such as driving.” The ADA went on to spell out what this means in terms of coverage: “For many patients, this will require testing 6—8 times daily, although individual needs may be greater.” It will take some time, unfortunately, for these new guidelines to take hold among insurance companies.

Why is that?

Well, I can see how monitoring might do little good if a person were simply handed a meter with minimal instructions regarding how, when, where and why to use it. On the other hand, a person empowered by knowledge who has the right tools is a well-equipped warrior, because diabetes is at least 50% a social disease. How you eat, move and act has a large impact on your blood glucose levels, and monitoring is a tool that tells you how and when you should be doing these things.

If those of us with diabetes were to rely only on the HbA1c[13] test (a measure of blood glucose control over two to three months) instead of self-monitoring to evaluate our blood glucose control, we would risk kidding ourselves about the quality of our blood glucose control. Not all HbA1c results are created equal, even if they appear to be exactly the same, since the test is a reflection of average blood glucose level. So, for example, you can get an average of 150 from a set of numbers that ranges from 125 to 175, but you can get the same average from a set that ranges from 75 to 225. Given what we are learning about the relationship between glucose variability and diabetes complications[14], it’s clear that it’s important to not only maintain a certain average blood glucose level, but also to keep the range of numbers as small and as stable as possible. Without the real-time feedback of a meter to inform you of the relationship between your actions and your glucose readings, true diabetes control is impossible.

So setting aside concerns about insurance and cost for the moment, is there an optimal monitoring schedule? Yes, but it’s not the same for every person (or for each type of diabetes, for that matter). The more complex your therapy is, the more variables there are, and therefore the more often you should monitor. All people who take insulin should monitor more often than those who take oral drugs. And people who take fast-acting insulin should monitor more often than those who take only basal insulin.

Another consideration is that some people just seem to have more stable overall blood glucose patterns, while other people seem to have inherently unstable glucose levels or to be hypersensitive to the environmental factors that affect those levels. Lifestyle, the driving force behind the social factors that determine 50% of diabetes control, should also be considered when it comes to monitoring. Shift workers with irregular hours, for instance, tend to have more unstable blood glucose patterns than people who work regular hours. The same is true for people with diabetes who work in high-stress jobs.

When “bad” numbers happen

It’s critical to remember two things when looking at your numbers, especially the ones around meals. The first is that you should focus less on altitude and more on spread. Put simply: Don’t look so much at what the numbers are, but rather at the differences between them. The second thing to remember is that there’s no such thing as a bad number.

“Bad” numbers are just good information. Too often, when our numbers don’t fit into the desired range, we think of them in a negative way. They are bad numbers. We are doing a bad job. We are bad people.

Don’t let yourself go down this road. Instead, celebrate an elevated number (or a below-target one, for that matter). You just discovered a problem that can be fixed! This is a victory. That high or low number would have been there whether or not you discovered it, and by finding the number through monitoring, you can now do something about it. The only truly bad number is an out-of-range one that you are unaware of.

The goals of monitoring

Smart monitoring is monitoring that helps you understand your diabetes, your body and your therapy. This understanding allows you and your healthcare providers to evaluate your current therapy and lifestyle, and to make changes if necessary.

If your blood glucose is not where it should be, it needs to be fixed. Sometimes you can fix it yourself. Insulin users — especially those who take fast-acting insulin — are especially fortunate to be able to make ongoing therapy adjustments on their own. And, of course, all of us have the power to make adjustments in what and how much we eat and in how we move.

Sometimes, though, blood glucose problems are beyond our ability to fix on our own. Diabetes is a progressive disease, and our bodies can adapt to many drugs and therapies so that they lose their effectiveness over time. If you’ve done all you can and your blood glucose is still too high, you’ve most likely outgrown your therapy, and you’ll need your doctor’s assistance to devise a new strategy.

Without smart monitoring, neither you nor your doctor will know enough about your diabetes to evaluate your treatment in a meaningful way or to change it thoughtfully if needed. Smart monitoring can give you an early warning when things aren’t going as planned, and it can help keep you on track when it comes to the 50% of your diabetes control that’s social in nature.

  1. [Image]:
  2. insulin:
  3. beta cells:
  4. ketones:
  5. fasting plasma glucose test:
  6. oral glucose tolerance test:
  7. kidney damage:
  8. high blood pressure:
  9. Somogyi effect:
  10. dawn phenomenon:
  11. hypoglycemia:
  12. insulin pump:
  13. HbA1c:
  14. diabetes complications:

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