A Million Factors That Influence BG Levels

Whenever we have a spike in blood glucose levels, we have to evaluate what seem to be a million different factors that could have caused it. 

These factors are not always obvious. 

When I was eating higher carb, I couldn't readily see the causes of these BG spikes. My BG numbers were naturally all over the board and I often blamed my pump or an infusion site issue for any unexplained high number.

Now with eating low carb, I can see these fluctuations easily and I'm providing a much more controlled environment to be able to evaluate and eliminate any unexpectedly high BG numbers.

It's all more clear.


There are more factors that affect blood glucose than we often consider, many of which are interconnected: 


Female hormones create an increase in insulin resistance for many women during their cycle. I use a 130% basal rate on my pump for 7 days leading up to my cycle, then it reverses and I need only 90% for another 2-3 days out of every month. This is not 100% consistent with all women of child-bearing age, but many experience shifts in BG levels during their cycle. Once women know to watch for this and expect it, the insulin adjustment become easier. 

Adrenalin, also a hormone, can create unexpected spikes in BG that are very hard to control. If you've ever been in a car accident or felt the fight-or-flight response to danger (or perceived danger) you've most likely seen an unexpected spike in BG levels immediately afterwards. (Also see "Stress" below)


Whether this manifests itself in overeating, lack of sleep or overall tension in the body, stress causes the release of epinephrine (adrenaline), glucagon, growth hormone and cortisol. As a result, more glucose is released from the liver and all can cause an unexpected increase in BG levels from insulin resistance. This stress could be caused by relationships, work, or any of the following: 

  • Lack of Sleep: Night waking, getting up to help young children at night and general lack of sleep can all cause cortisol (a stress hormone) and leptin (a satiety hormone) release, which in turn causes mood swings, food cravings and overeating. "Sleep loss is associated with an increase in appetite that is excessive in relation to the caloric demands of extended wakefulness.

    The regulation of leptin, a hormone released by the fat cells that signals satiety to the brain and thus suppresses appetite, is markedly dependent on sleep duration. " - The Impact of Sleep Deprivation on Hormones and Metabolism

  • Pain: Any pain reaction in your body is a stress reaction. Practice stress and pain reduction techniques. Take ibuprofen to ease pain (avoid Acetaminophen not only because of this study, but also because it can interfere with CGM readings, if you use one.)


Illness can cause insulin resistance as your immune system is fighting off the invading bugs. Rest, plenty of fluids and keeping up with your correction doses of insulin can help to avoid potentially fatal Diabetic Ketoacidosis (DKA). Test your blood glucose levels often and if you are not improving, are vomiting and have high BG levels (or if you are in doubt whether you are in DKA) go to the emergency room/call an ambulance immediately. 

Anemia (Vitamin/Mineral deficiencies):

While some forms of anemia might not directly cause spikes in BG numbers, any vitamin or mineral deficiency can cause intense and uncontrollable cravings, which can lead to overeating on a given item. Deficiencies in Vitamin D can cause insulin resistance, so if you are deficient, consider supplementation with Vitamin D3/K2. This is available over the counter. Talk to your medical staff regarding the appropriate dosage for you. Iron deficient anemia can have a direct affect on A1c numbers, so that is one reason to talk to your doctor about supplementation to get your levels to the optimal range. 


The list is of medications that effect BG levels is long, and always growing as a new medication is released and more is known of the effect current medications may have on the public. See Dr. Bernstein's Diabetes Solution, Appendix C, "Drugs That Can Affect Blood Glucose Levels", pages 484-493. Also see this link for a list of 390 Drugs That Can Affect Blood Glucose Levels


Protein causes a delayed spike in BG levels as our body converts the protein to carbohydrate through gluconeogenesis. This might not be a very large spike at all with fish or chicken, but can be a large and delayed spike in the case of beef.

I usually see protein spikes with beef 4-5 hours after eating that can raise my BG levels 100+ points. This is difficult in the evening if I eat a large portion of beef for dinner and I'm struggling with a protein spike right before bedtime. Frequent BG testing and awareness that this will happen can help you to anticipate the spike and/or reduce your portion size/change your menu to include beef earlier in the day.

Inaccurate calculations of food and/or insulin:

Unless you are weighing your food, using an accurate online calculator and know your precise insulin correction factor, (or maybe you just eat the dame thing every day?) chances are you'll make some mistakes in calculating insulin doses. This is very easy to do, especially with processed foods as the nutrition labels can have up to 20% variability in accuracy. It makes our jobs much more difficult. 

Hidden carbs also fall into this category. For example, Maltodextrin is often used as an additive to processed foods and shows 0 grams of carbs, when it can have a profound effect on BG levels. Another additive is cellulose powder or potato starch, often added to pre-shredded cheese. While some individuals can eat these additives with no problems, others (like me) see an unexpected spike after eating a seemingly low carb food. 

Stick to eating whole foods whenever possible. Practice The Law of Small Numbers. Small inputs make small mistakes. 

Malabsorption of insulin:

If you are taking large doses of insulin at one time, the possibility of malabsorption is greater. For optimum absorption, Dr. Bernstein recommends splitting injections to no more than 7units of insulin per injection site on the body. This gives the best chance for all of the insulin to make it into your blood stream without an immune attack.  

Dawn Phenomenon: 

The dawn phenomenon is the morning rise in BG levels, usually upon waking due to hormone release. Some people joke that their BG rises immediately when their feet hit the floor, others do not experience the rise until well after waking, others do not experience the dawn phenomenon at all. 

This usually starts between 2:00-8:00 AM, but depends on your sleep cycles. If you wake unexpectedly during the night, perhaps thanks to a pet or child, the dawn phenomenon may start much earlier. 

I usually test my BG immediately upon waking and give 1 unit first thing in the morning. Then give another 1.5 unit for eggs a couple hours later.

More information about the dawn phenomenon can be found here


As a general rule, cardio-based exercises will drop your BG levels, while weight training/heavy lifting will raise BG levels. Most fitness enthusiasts find that they can balance their BG levels with a combination of both weights and cardio during their workouts, or weight training with periods of active rest in between (such as running in place, jump rope or jumping jacks for a minute between lifting sets). 

This is certainly not an exhaustive list of the factors that can cause blood glucose spikes and the things we need to consider every day.

No wonder people EXPERIENCE T1D BURNOUT and struggle with diabetes management. This is one of the many reasons that we're committed to providing information regarding the low carb way of eating for diabetes management.

When you remove some of these factors that can raise BG levels, such as:

  • Large quantity of carbs during a meal

  • Too large of correction of a low (hypoglycemia)

  • Underestimating insulin dosages

  • Malabsorption issues due to huge insulin dosages

...your stress level will also decrease because your BG numbers are more steady, giving you more confidence in your own body and in your ability to manage diabetes.

the low carb way of eating simplifies diabetes management. 

Have you experienced other factors that influence your BG levels that we didn't mention here? Leave us a comment and tell us your additions to the list!