Factors that Affect Blood Glucose

What Raises or Reduces BG? An Intro to Effectively Managing Blood Sugar Swings

A number of factors impact your child’s blood glucose reading at any given moment in time. Effective glycemic control (that is, reducing highs and lows, and maximizing the time your child spends in the target blood glucose range) requires a balance of these factors. Your child’s blood glucose and A1C may benefit from proactive changes in how you or your child manages his diabetes, as well as changes in how you react to certain factors. Some of these factors decrease blood glucose, while other factors lead to an increase, as follows…

Factors That Raise Blood Glucose

Food and Drink Consumed

When your child eats foods containing carbohydrates (or protein, to some degree), her blood glucose will rise.

The goal of effective blood glucose management is to match the food bolus (insulin dose to cover food) as closely as possible to the food consumed, so that blood glucose rises as little as is reasonably possible, and returns to the target range after meals and snacks.

More on the effect of FOOD on blood sugar:

Nutrition section

Hormones (released due to growth, stress, menstruation, etc.)

If your child is in a growth spurt, has entered puberty, is menstruating, is in a period of elevated stress or excitement (such as exam time, travel, or exciting visits with grandparents or to an amusement park), you may need to make adjustments to the insulin she receives, possibly giving more insulin than her body would require in non-growth, non-stress, non-hormonal times.

Tips from the Trenches

When we travel, even if activity levels stay about the same, we find that because of stress and excitement, we need to increase our son’s basal insulin significantly or else we are constantly battling high blood glucose.

Factors That Lower Blood Glucose


Your child’s blood glucose will be affected by the amount of insulin that is currently acting (from recent insulin doses), including:

You may find that changes need to be made periodically to these rates and ratios to meet the changing needs of your child’s body for insulin. Also, If your child is on a Conventional Insulin Program and there have been or will be changes in his eating habits/planned meals, insulin doses may need to be adjusted.


If your child will be participating in planned exercise, you may need to adjust insulin doses or provide extra carbs to accommodate for the blood-glucose-lowering effect of physical activity.

More on the effect of physical activity on blood sugar:

Factors That May Raise OR Lower BG

Some things can have different effects under different conditions or for different individuals…


If your child is sick, his insulin doses will likely need to be adjusted (either up or down) throughout the course of the illness.

Tips from the Trenches

We have found that our son has several unexplainable lows for about 3 days before he shows symptoms of a cold or flu-like illness. Just when we’re wondering “what the heck is going on here?!” he starts to cough or get congested, and then highs often become the norm for the next few days.


Although stress generally leads to high blood glucose and some kids battle high BG at exam time, for example, we have heard from more than a few kids that lows are more common for them just before or during school exams.


Although exercise most commonly lowers blood glucose, there are circumstances in which exercise actually raises it.

More on physical activity that could RAISE blood sugar:

When your child experiences any of the above factors, or you notice that her blood glucose is often below or above the target range, you may want to explore some of these factors in more detail. For more information, click on any of the underlined topics above for more information. Many parents choose to consult with their child’s diabetes health care team for assistance with changes to the blood glucose management regime.

The above information was reviewed for content accuracy by clinical staff of the Alberta Children’s Hospital Diabetes Clinic.