If you’re using a blood glucose meter or glucometer (BGM) to manage your diabetes, checking your blood sugar is critical — and if you take insulin, you’ll need to check several times per day. The numbers on your BGM can tell you how well your body is handling the food you eat and if your medication dosages need to be adjusted. Checking your blood sugar every day is also for your immediate and long-term safety.
Things to consider about when and often you should check your blood sugar:
What the American Diabetes Association (ADA) says: The ADA’s recommendation is broad but includes a few critical points: If you take insulin, you should be monitoring your blood sugar daily. Overall, blood sugar monitoring frequency should be tailored to each individual based on goals, current blood sugar levels, changes in medications, etc.
If you take insulin via injections or pump, your healthcare team should prescribe a BGM and/or CGM (continuous glucose monitor) to help you monitor your blood sugars. When taking insulin, your blood sugars can fluctuate quickly and dramatically if your doses aren’t fine-tuned for your body’s needs! If your BGM says your blood sugar spikes 100 points after breakfast, for example, that tells you and your healthcare team that your insulin doses need a major adjustment!
If you don’t take insulin, checking your blood sugar every day is still very important. Your levels could be creeping up gradually or quickly, but you’re not feeling the symptoms or aware of the fluctuations. If your healthcare team feels comfortable with the stability of your blood sugar levels — meaning you are maintaining your A1C goal — you might be given the green light to cut back significantly on regular monitoring.
You can’t manage what you don’t know! Here’s a look at what times of day you might consider checking your blood sugar.
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Okay, let’s take a look at important times of day to check the ol’ blood sugar.
When you wake up
Your blood sugar first thing in the morning says a lot about how your body and medications are working. It’s been at least eight hours since you ate anything, so that removes the biggest variable: food! This is probably the most important time of the day to check your blood sugar, especially if you have type 2 diabetes and do not use insulin.
If you’re consistently waking up above your target blood sugar range, that’s a clear sign for you and your healthcare team. While being a little bit above your target range isn’t necessarily cause for alarm, being significantly above your target range means it’s time to take action.
It could mean you need to adjust existing medication dosages, consider starting a new medication, or make some adjustments in your overall lifestyle habits that impact insulin resistance.
On the other hand, if you’re waking up low, it could suggest you’re getting too much of a medication — specifically insulin or sulfonylureas! Keep in mind that if you start another medication, like Ozempic or Mounjaro, this could mean you need to adjust your insulin doses to prevent lows, even though Ozempic and Mounjaro do not cause hypoglycemia on their own. Either way, it’s time to chat with your healthcare team.
Checking before every meal sounds tedious, but it’s very important — especially if you take insulin or your A1c is higher than your goal.
It’s important to know what your blood sugar is before eating because we’re also going to talk about checking your blood sugar after eating! If your blood sugar was high before the meal, that’s critical information for you and your healthcare team.
Heading into a meal with a high blood sugar could mean a few things:
You didn’t get enough insulin with your last meal. You aren’t getting enough basal/background insulin. You need to consider starting insulin therapy or another diabetes medication. Your body, generally speaking, needs more support managing your blood sugar.
Checking your blood sugar before eating sets you up for success!
Two hours after eating
While it can certainly take more than two hours for a meal to digest, this is a good indicator of how well your body is handling the meal you ate.
If you take insulin, high or low blood sugars after eating suggest you’re getting too little or too much insulin. This tells your healthcare team your doses and insulin-to-carbohydrate ratio need fine-tuning!
If you don’t take insulin, high blood sugars after eating suggests your body needs more support from diabetes medications or you might consider making changes in your meal choices.
The information you get from that post-meal BGM check can also motivate you to make some adjustments in what you’re eating. That giant bowl of cereal or pasta might be more than your body can handle. When you see the evidence on your BGM, it’s hard to ignore. That doesn’t mean you can’t ever eat pasta, but it might mean you want to consider reducing the portion size.
Before and after physical activity
Exercise can cause rapid changes in your blood sugar level because your body needs more fuel to perform!
Aerobic exercise: Also known as “cardio exercise,” this type of physical activity increases how quickly your cells take up glucose to use that glucose for energy. If you take insulin, this means your blood sugar can drop very quickly. Aerobic exercise includes walking, jogging, vacuuming the house, gardening, cycling, etc
Anaerobic exercise: Anaerobic exercise is different! It can actually cause your blood sugar to rise thanks to “gluconeogenesis” — when your body converts lactic acid into glucose to use for fuel! Your liver can also release stored glucose during and after anaerobic exercise. Anaerobic exercise includes things like strength training, CrossFit, and sprinting.
Regardless of what type of exercise you’re doing, always carry fast-acting carbohydrates with you to treat potential hypoglycemia.
Before you settle in for the night, it’s critical for your health and safety to give that ol’ blood sugar level a look. You’re going to be snoozing for eight hours!
Check your blood sugar before bed is critical because:
If you take insulin or other diabetes medications, you’ll want to make sure you’re in a safe range before falling asleep. If you’re low, you’ll need a small snack. If you’re high, you may need a correction dose. This time of day also lets you know how well your insulin dose covered your dinner and/or dessert.
If you don’t take insulin, that pre-snooze blood sugar tells you how well your body is handling dinner and/or dessert. If you’re consistently above your target range, it’s a clear sign that your food choices might need some adjusting or that you need support from diabetes medications.
That 8-hour snooze is 25% of your entire day’s worth of blood sugar levels! Getting your blood sugar into your goal range throughout the night can have a big impact on your A1c, too. But you can’t manage what you don’t know — so you’ve gotta start checking your blood sugar before bed.
The bottom line
Collect that data and talk to your healthcare team! The more often you check your blood sugar, the better you will understand your condition and how to manage it.
If you don’t use insulin, your doctor may recommend only checking once a day or a few times a week, but the more data you gather, the more you know about your diabetes health. You might also find you just need to check more often for a week or two to see how things are going. Get that data, talk to your healthcare team, and never give up!
American Diabetes Association Professional Practice Committee. Diabetes Technology: Standards of Care in Diabetes—2024. Diabetes Care. December 11, 2023.