When to Test Your Blood Glucose
Common Health Issues

When to Test Your Blood Glucose

Whether you have Type 1, Type 2 or gestational diabetes, your goal is to keep your blood glucose levels as close to normal as possible, with a plan that works for you. The only way to know for sure whether you are meeting your goal is to test your blood glucose levels. Testing also helps tell you know when problems arise—when you are having low blood glucose reaction or when you are at risk for ketoacidosis or hyperglycemic hyperosmolar state, for example. And monitoring can tell you whether you need to make any adjustments in your eating, exercise, or insulin schedule.


When to Test Your Blood Glucose

When you test and how often you test depends on your reasons for testing. If you use insulin and are testing so that you can adjust your next insulin injection or want to know what you should eat at your next meal then you need to check your blood glucose every time you plan an injection or meal. This would mean you would need to test three to four times a day. If you exercise regularly, you may also want to add another test to see whether you need to eat anything before you begin.


If you are aiming for tight control, you need to monitor at least four times and perhaps five times a day. You should test before each meal and before bedtime every day, and in the middle of the night (around 3 a.m.) at least once a week. When you monitor less than four times a day, glucose control worsens.


On the other hand, maybe you are just trying to prevent hyperglycemia and diabetic ketoacidosis and aren’t so concerned about keeping your blood glucose levels close to normal all the time. If you have adopted a more relaxed schedule and are taking insulin once or twice a day, then you may opt to monitor twice a day.


If you have Type 2 diabetes, then your blood glucose level is probably somewhat stable over the course of the day and you don’t have to monitor quite often. If you are taking oral medications to control your blood glucose, you don’t have to monitor as often as someone who is taking insulin. When you first begin taking an oral agent, you may need to monitor more frequently as you and your health care team try to figure out the right dose. 


You may also need to monitor frequently whenever you need to change your dose or when there is a change in your care plan (such as new exercise routine). In addition to testing before breakfast and dinner, you may also want to test 2 hours after breakfast and dinner to see how well your plan is working and whether any changes are needed. Once your blood glucose levels are under control, testing only once or twice a day may be all you need.


If you have Type 2 or gestational diabetes and you manage without any insulin or medications, then you may opt to test less often once your blood glucose levels are under control. This could be as often as once or twice a day or as little as three to four times a week. On certain occasions, you might want to test more often, such as after a special dinner or extra-strenuous workout.


You should also consider testing whenever you are not feeling quite right and you don’t know why. If you are not feeling well, you need to test more often. If you are feeling a little shaky after your normal 1km run, you need to know why. Maybe you suspect hypoglycemia and take an extra dose of carbohydrate. But your glucose levels may actually be high and something else might be going on. The only way to tell for sure is to monitor your blood glucose.


You should discuss when and how often to test with your diabetes health care team. Suggested times to test include:

  • Before breakfast, lunch, dinner or an especially big snack
  • Before you go to bed
  • 1 to 2 hours after breakfast, lunch, dinner or an especially big snack
  • At 2 or 3 am

Some suggested times when you should do extra tests:

  • When you are ill
  • If you suspect hypoglycemia
  • Before you drive (if you take insulin or sulfonylureas)
  • When you are physically active
  • If you start taking a non-diabetes or over-the-counter medication that could affect your blood glucose level or your ability to recognize hypoglycemia (talk to your doctor or pharmacist about these possibilities)
  • If you have frequent insulin reactions overnight or wake up with high blood glucose levels (over 180mg/dl)
  • Whenever you change your insulin injection plan, your oral medication dose, your eating plan or your exercise plan
  • When you have lost or gained weight
  • When you are pregnant, thinking about becoming pregnant or think you may be pregnant
  • When you have trouble recognizing the warning signs of hypoglycemia
  • When your blood glucose levels have been dangerously high or low (outside your acceptable range)
  • When you are on intensive insulin therapy



Sources and References

The Diabetes Problem Solver: Quick Answers to Your Questions About Treatment and Self-Care by Nancy Touchette

Self-Monitoring of Glucose by People with Diabetes: Evidence Based Practice by M Gallichan


Rich Health Editorial Team

Health Research

Rich Health Editorial Team is made up of medical practitioners and experienced writers who provide information for dealing with health issues in a simple and easy-to-understand manner