If you’re new to diabetes, or trying to get your head around it for a loved one, you’re surely hearing the term “blood glucose management” a lot. What does that mean? Well, it’s the heart of controlling diabetes, so to speak.

We proudly present this “BG Management Primer” about what makes our blood sugar levels go up and down, and what we can do about it. Consider this a great introduction for newbies and refresher for the rest of us.

For the veterans of living with diabetes: Please add your input on our Facebook page. Let’s share our collective wisdom for the greater good!

The essence of diabetes is the fact that there’s too much sugar flowing through our bloodstream, and our bodies are not able to regulate it the way a healthy person’s body does. In type 1 diabetes (an autoimmune condition), the body actually kills off the pancreatic cells that make insulin, so there’s no natural insulin at all — therefore we have to inject it (or inhale it).

In type 2 diabetes, the body has become “resistant” to the insulin present, which can be offset by lifestyle changes and oral medications. But in many T2 cases, after a decade or so, the resistance becomes so strong that those methods no longer work and insulin injections are necessary.

Some people have likened having diabetes (either kind) to being a car with a manual transmission; our pancreases don’t automatically regulate the glucose in our blood. Rather, we have to do it manually, through medications, diet, and exercise.

In fact, regulating the levels of glucose in our blood is all about the balance of those three things: the physical activity we do, the medications we take, and the food we eat (specifically, carbohydrates).

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Image: DiabetesMine

Food makes your BG levels rise, while physical activity and medications generally make it drop. The trick is not to overdo it on any of these, in order to keep BG levels from surging or plummeting.

With type 1 diabetes in particular (people taking insulin), it’s especially challenging that these factors can overlap and confound each other. If you have a dose of insulin “on board” when you start exercising, for example, the effect of that medication will get turbo-charged and you’ll very likely experience hypoglycemia (dangerous low blood sugar, that can make you pass out or cause a seizure). Or if you eat a very high-fat meal, that will slow down carbohydrate absorption so the insulin you took may hit too early, and you will go too low before getting too high later on. Ugh!

Even with type 2 diabetes (non-insulin therapy), never let anyone tell you that balancing these factors is easy if you just follow doctor’s orders. Quite the contrary: Since BG levels can also be impacted by all sorts of variables like stress, lack of sleep, menstruation, and other medication interactions, it’s very easy to make mistakes!

In short, BG management requires a lifetime troubleshooting approach. There is no “bad” versus “good” type of diabetes; we all have to manage our BG on a regular basis to avoid the physical damage diabetes can do.

The American Diabetes Association (ADA) sets goals for “nonpregnant adults with diabetes” as between 70 to 130 mg/dL (or 4.4 to 7.2 mmol/L for our European friends, who use a different measurement system).

That is, you’re not supposed to dip below 70 mg/dL to avoid dangerously low blood sugar, and ideally not top out over 180 mg/dL, even after meals. The latter is a lot harder than it sounds, given that carbohydrates (which turn to sugar in the bloodstream) can easily make your BG skyrocket immediately after eating.

The thing about BG levels, especially for folks who take insulin, is they’re very contextual, based on all the factors that make your glucose go up and down (see below). If you’re about to do some heavy exercise, a slightly elevated glucose level is probably a good idea, to safeguard you from going too low. Whereas if you’re about to indulge in some birthday cake, running a bit low may not be bad.

The main cause of high BG is mainly food, specifically carbohydrates. These are the sugars and starches found in grains, fruits, dairy products, and some vegetables. It also includes all sugary foods like sweets, fresh fruit, and sugar itself, along with all manner of starchy foods (bread, pasta, potatoes, rice) that break down to glucose in your body.

People with diabetes absolutely need to be aware of the carbohydrate content of their food, because limiting carbs is an important tool for regulating BG levels.

A host of other factors can make your BG levels rise, too, including illness, infection, stress, lack of sleep, and menstruation. Basically, anything that puts a burden on your body is likely to increase your insulin resistance, meaning even injected insulin will be less effective than usual and you may need more to bring your BG levels down.

Low blood sugar is mainly caused by exercise and medications, especially insulin.

That is, physical activity of nearly any kind that makes your heart beat a little faster will also cause your muscles to use more glucose, which lowers your BG levels. It also makes any BG-lowering medications in your body work more effectively. This can be a good thing but can also be dangerous; if you have too much insulin “on board” when you begin exercising, you may very well “crash” and have a hypoglycemic episode.

Experts warn you should not begin strenuous exercise if your BG is already too high — over 250 mg/dl — because this can cause your body to pour extra glucose into your bloodstream, which in turn can cause dangerously high BG (hyperglycemia) that leads to diabetic ketoacidosis (DKA), a state than can lead to a coma.

Sound complicated? It is. But despite these warnings, exercise is still your friend!

We can’t overemphasize the importance of being physically active. Regular exercise not only reduces insulin resistance and improves BG control, it also eases tension and anxiety; improves sleep; gives you more energy and a sense of well-being; and even improves your sex life, according to clinical studies. For more, check out a global initiative called Exercise is Medicine.

“High blood sugar” (hyperglycemia) is defined as over 130 mg/dL before eating, and over 180 mg/dL following meals. For people with diabetes, getting to 180 mg/dL can be a common occurrence, but anything persistently over 200 mg/dL should be cause for some alarm — or at least some immediate action, like additional insulin or physical activity to bring levels down.

The symptoms of high blood sugar are feeling irritable, headachy, fatigued, hungry, or nauseous. If BG spikes above 400 mg/dL, seek treatment immediately because, as noted, you could be heading into DKA.

“Low blood sugar” (hypoglycemia) is generally considered 70 mg/dL or lower. Symptoms include feeling nervous, dizzy, shaky, weak, and/or hot and sweaty. You can also experience tingling skin, difficulty sleeping, and bad dreams.

Note that low blood sugar is more immediately threatening than high. If not treated right away with sugar (fast-acting carbohydrates), you are likely to pass out or have a seizure. If you have diabetes, it’s advisable to carry emergency sugar at all times. This can include glucose tablets or gels made specifically for treating hypoglycemia.

The “gold standard” lab test for blood glucose control is called the Hemoglobin A1C. It’s usually conducted in a clinic or hospital lab, although all that’s really needed is one big drop of blood for an accurate test. It produces an average level of BG control over roughly the past 3 months, expressed as a percentage.

The ADA recommends an A1C level of less than 7 percent, to match the BG levels of non-diabetic people.

For many people with diabetes, hitting that A1C level is a constant struggle. It is especially frustrating given that your A1C result is used by everyone from your doctor to your insurance company to friends and family to judge how well you’re doing with your diabetes management.

Lately, there’s been a backlash against overemphasizing the A1C because it doesn’t really reflect your daily glucose control, nor your well-being in any way.

Remember that the A1C is calculated as an average or a mid-point of all your glucose values over the past 3 months. It’s possible to have a “perfect” A1C result of 6.5 percent that in reality is nothing more than a mid-point between several weeks of severe highs and lows. Not good.

If, however, your A1C is slightly elevated at, say, 7.2 percent, and you did not have frequent low BG values, that means all your levels over the previous 3 months were pretty good. This is because if you were hitting frequent highs, your A1C would also be much higher.

Clinicians, researchers, and advocates have been putting a lot of emphasis in recent years on “Time in Range” rather than A1C. This looks at how many hours per day are spent in the ideal BG range of roughly 70 to 180mg/dL, which is MUCH more meaningful for people navigating a day-to-day existence with diabetes.

“Fasting blood sugar” is a term that refers to both your BG level upon waking in the morning and a lab test of your glucose levels after not eating for a period of 8 hours.

That’s right, for a fasting blood glucose test, you can’t eat or drink anything but water for 8 hours prior. Most people schedule these tests first thing in the morning, so they don’t have to go hungry during the day.

In people who already have diabetes, this number can be used to gauge overnight BG control. However, it’s most commonly used when diabetes is suspected, as in:

  • A fasting BG level of 100 to 125 mg/dL indicates prediabetes
  • A fasting BG level of 126 mg/dL or higher means a diabetes diagnosis

When home glucose meters became mainstream in the 1980s, they revolutionized diabetes care. Before that, all people had was a urine test that took 24 hours or longer to produce results. Now people could actually know their own BG level, right in the moment!

Today, these glucose meters are getting increasingly high-tech, with Bluetooth wireless connections to smartphone apps and the capability to crunch the data collected and provide feedback.

With or without these bells and whistles, a glucose meter remains the essential tool for managing diabetes. Most patients get a basic meter for cheap or free from their doctor at diagnosis, and it’s the test strips that cost them money over time.

Bottom line is: If you have diabetes, you need to test regularly. If you have type 2 diabetes and are not taking insulin, it may be sufficient to test every morning and evening, and then periodically before and after meals to gauge how certain foods affect your BG levels.

If you take insulin, you’ll need to test much more often to stay safe and sane. Test in the morning, bed time, before and after meals, before and after (and sometimes during) exercise, and ANY TIME that you feel the slightest bit light-headed or “off.”

The first Continuous Glucose Monitor (CGM) hit the market in 2007 and has really changed the game for anyone who needs to test frequently throughout the day. It’s especially life-saving for those who experience “hypoglycemia unawareness,” meaning they no longer feel the natural symptoms of plummeting blood sugar. Being able to wear a sensor that gives constant readings and alarms when you are out of range is revolutionary!

Image via Dexcom

CGM now provides the “24-hour movie version” of your BG levels versus the “snapshot photo version” we get from traditional fingerstick meters.

There are currently three CGMs on the market: one from Dexcom, one from Medtronic, and a slightly different variety called Abbott FreeStyle Libre. All three include a small sensor that’s attached to your skin with an adhesive, and penetrates the skin with a tiny needle called a cannula. These sensors contain an electrode that helps measure your glucose levels from the “interstitial fluid” between the tissue cells rather than directly from your blood, like a fingerstick meter does.

Your BG results are beamed to a handheld “receiver” or, increasingly, to a smartphone app, where you can also manage settings and alarms. See this guide to CGM systems and how to choose one.

Note that the biggest challenge with CGM is getting insurance coverage for this expensive device, something the D-community has been heavily advocating for a decade now.

Traditionally, all diabetes patients were encouraged to keep records of their BG test results in written logbooks. Thankfully, today both fingerstick meters and CGM devices store this data for easy reviewing.

What to do with all that data? Obviously, the immediate result can help you decide what to do next: Do you need food to bring up your BG? Or do you need more insulin to bring it down? And there are an array of logging tools and apps that can help you analyze the aggregate data, to spot trends, and to discover problem areas. For example, does your BG regularly spike in the early mornings, something called Dawn Phenomenon? See this guide to 5 Easy Ways to Actually Learn from Your Diabetes Data.

While the pressure to review your data can be one of the biggest annoyances of living with diabetes, it really is important to be able to see how your numbers change over days and weeks. This helps you and your doctor spot trends, like, “Why I am always too high on Thursdays?” or “I seem to be going low regularly after breakfast.” This can help you make changes in your routine for better BG control.

The thing about this data is that your BG numbers on their own can only tell so you so much — whether you were running high or low. That’s not the full picture without any information on the medications you took, the food you ate, and the exercise you did. (Those Big Three factors.)

In other words, you ideally need to log the number of carbohydates you ate per meal and make notes on exercise and dosing alongside your BG data — at least for short periods in order to gain insights. This is where the technology tools are really helpful. New smartphone apps make it really easy to record all those factors. Some popular apps to know about are mySugr and Glooko, and the connected meters Livongo and One Drop. If you’re using a CGM, your BG data is being automatically recorded, and you can actually add notes about food and exercise in the device’s companion app.

If it isn’t obvious by now, BG management is a big balancing act. It’s all about working to stay in range (that “glorious middle”) as much as humanly possible. This requires being constantly aware of your food and medicine intake, and physical activity output.

Unlike people with healthy pancreases, the choice to eat a sugary dessert or take the stairs instead of the elevator can have both an immediate and long-term effect on our health.

To reiterate, there are LOTS of factors that impact your BG levels — and sometimes it even feels like the direction the wind is blowing is playing a role! That’s because BG management is not an exact science. Every day presents new challenges, and often the strategy you used yesterday or last week does not produce the same results.

Therefore, one of the most important things to know about BG management is not to beat yourself up about it!

Yes, you need to put in the work, but it’s imperative not to see every glucose test as some kind of pass/fail exam. (You’re just checking, not “testing”). Don’t be guilt-ridden; simply keep on plugging away with your daily efforts.

Feel free to tell your friends, family, and especially your doctor we said that!


Amy Tenderich is the Founder & Editor of DiabetesMine, a news and advocacy resource she started after her own diagnosis with type 1 diabetes in 2003. She is co-author of “Know Your Numbers, Outlive Your Diabetes,” and has become a nationally known patient advocate, public speaker, researcher, and consultant. When not working, she enjoys spending time with her three daughters, and hiking the great outdoors in the San Francisco Bay Area.