My husband and I both wore continuous blood glucose monitors for 2 weeks, mostly out of curiosity; to see how our blood glucose fluctuated throughout the day, the impact of various foods and beverages, and whether we could really sense our “highs” and “lows” based on how we felt. We used the FreeStyle Libre, which has a sensor implanted in the surface of the upper arm, and uses a phone app to get an immediate readout of current blood glucose levels.

The take away lesson from this experiment was that though we are both experts at blood glucose control in our own fields, and though the rules we teach patients to follow are helpful, it is incredibly eye-opening how unique each individual is in what does or does not impact their blood glucose levels.

My husband was fairly steady. He did not go up or down much when he ate high carb foods, but skyrocketed when he ate sugary foods, even in tiny portion sizes. He ate a small cookie and his blood sugar went up to 180. A couple of days later, he had a small bowl of granola cereal and hit 190. However, when he had a big plate of white rice or a large naan bread, nothing happened, his blood sugar stayed about 110!

My case was totally different. I started the 2 week experiment with a bad cold, and was taking an over the counter decongestant. I did not think much of it at the time, but as soon as I started taking my blood glucose readings, I was shocked to find that I was in the 150’s to 160’s after meals such as brussel sprouts and roasted chicken or a large kale salad with mixed vegetables. Of course, I am aware that kale and brussel sprouts do have a moderate amount of carbs and my portion sizes are large, but since those meals had no “starches” per se, and since I am at a healthy weight and quite active daily, it seemed very odd. Even more concerning was that my fasting blood glucose was 110-120! I was starting to get nervous. I wondered if I had somehow developed diabetes over the past year and just did not realize it because I keep my diet so healthy. Thankfully, when I discontinued the decongestant and recovered from my cold (physical or psychological stress can increase blood sugar in many individuals), my blood sugar suddenly went back to a healthy range of 70-80 fasting and about 110 after meals!  What a change!  I also discovered that I respond very strongly to caffeine. Luckily, I don’t consume much, but I do have a cup of coffee every morning, and must have a large adrenaline response from it (no wonder it feels so good to have my morning cup!), because even when recovered from my cold and on an empty stomach, my blood glucose went up to the 160’s to 170’s after one serving of coffee (I use instant coffee to be able to measure the amount of caffeine I consume, since brewed coffee varies significantly), which is quite high! I also found that I had a moderate blood glucose increase during exercise, which sounds counter-intuitive. Physiologically, it would be expected for exercise to lower blood glucose, since the body is using glucose reserves to fuel exercise. Again, this is a case where the adrenaline response from exercise can increase blood glucose temporarily (also glucose is being mobilized from stores to be used to fuel the activity), and then it will decrease over time after exercise has concluded. Some people respond like I did, others do not, it depends on individual metabolism, intensity of exercise and amount of fuel available in the body for use.

I would highly advise anyone who is able to do so to follow their blood sugar for 1-2 weeks using continuous blood glucose monitoring. It is an eye-opening teaching tool. If this is not possible, my advice is to understand that while it is good to follow generalized blood glucose management tips meant for the average person, also understand that the effects of various stimuli on blood glucose varies greatly from person to person. If you are having symptoms of high or low blood sugar, or not reaching your health improvement goals, I recommend keeping a food, medicine, supplement, activity, stress and lifestyle journal for 1-2 weeks and record everything you subject your body to (food, medications, stress, exercise, etc) and how you feel (energized, jittery, fatigued, difficulty concentrating, and so on). You may be able to make connections on your own regarding how various factors disproportionately impact you. If you have the ability to see a dietitian or physician after you do the tracking, they can help to shed light on what is causing your symptoms or lack of progress as well.