Maybe, the brave monster tamers among you have already noticed this phenomenon? Everything is perfect: you are well adjusted, have your blood sugar well under control - if it weren’t for the high fasting blood glucose values. However, there can be different explanations for this.
First of all, it can be totally normal that the amount of insulin during the night is simply not enough to prevent the blood sugar from rising which means that something is wrong with the basal rate.
What do we need basal insulin for anyway? Here is just a quick recap of the basics: the liver continuously releases some sugar into the blood between meals and at night in order to keep the blood sugar at a healthy level. Of course, insulin is needed for this sugar to be transported to the cells. The basal insulin that should normally make up 40-50% of our total insulin requirement is needed for this continuous flow of sugar. And of course the demand can also change over time. For example, if you catch a cold or get a fever - which probably everyone could notice already at some point by looking at their values.
Changes in the demand for insulin can also occur gradually, for example, when gaining or losing weight, aging or hormones are changing as it happens during the menopause for women.
Normally, the basal insulin demand of almost every person rises in the early morning hours (mostly between 3 a.m. and 6 a.m.). This is normal. However, the rise can vary in intensity. This is called the dawn phenomenon. The reason for this is a more intense release of growth hormones, adrenalin, cortisol and glucagon, which are also known as the antagonists of insulin. With basal insulin injections that cannot be adjusted on an hourly basis, this problem is often not as easy to solve, but an insulin pump can deliver more insulin in the hour depending on the higher demand of insulin.
Now, coming to the topic of sleep: those who are stressed, those who sleep badly - and oftentimes too little (under 6 hours) - tend to have higher cortisol levels. It is important to remember that cortisol and insulin aren’t best friends, because cortisol counteracts the insulin which results in increased blood sugar values. Approximately 1.5 hours after going to sleep, our insulin demand reduces. At night time, between 2 a.m. and 3 a.m., we have the lowest insulin requirement. When we get up, the demand rises sharply, which is again due to hormones that regulate our blood pressure. Those that wear a continuous glucose meter (CGM) can analyze those processes very well.
Dinner, protein and fat
Who doesn’t know that feeling of coming home late after work with a monstrous hunger and right before going to sleep having a big meal? At night time, when lying in bed, we are digesting very slowly and now the late meal can take revenge with a high fasting blood glucose value. Especially, if the meal contained a great amount of protein and fat, for example like eating a steak with a salad. After a meal like this, a delayed rise in blood sugar values can be expected. The amount of protein in our food influences the blood sugar values but slowing down blood sugar absorption. with a time difference. Depending on the amount, the sugar rises about 3-8 hours later. On the one hand, protein building blocks (amino acids), which have an effect on the blood sugar, are converted into sugar, but there are also amino acids that lead to an increased release of glucagon which causes the liver to release more sugar. So, for your next dinner keep an eye on your protein-fat-calculations.
Watching a funny video on YouTube or binge-watching our favorite series on Netflix? Most of the time, we combine the time in front of the screen with yummy snacks that make the TV evening really relaxing. And relaxation is good for you. This can, however, also be tricky at times because snacking in the late evening or night can be the reason for high blood glucose values, as well. Especially if you forget the insulin.
Tip: If possible don’t snack at all (ok, ok, this is not a good one ;)). But, if you have to, then do remember to inject your insulin. Each carbohydrate exchange, which is equal to 15 grams of carb makes the blood sugar rise between 30-50 mg/dl (1.7-2.8 mmol/l) and this can easily be reached with a few chips.
Too high blood sugar in the evening
Some people start into the night with a high blood glucose value for various reasons. In this case, work towards getting your blood sugar close to your target range in the evening. Your basal insulin dose is appropriate when your blood sugar stays steady or varies no more than 30 mg/dl. However, those who start into the night with a high blood glucose value often wake up with a high blood glucose value, as well.
Last but not least, a high fasting blood sugar can also be caused by a hypo over night. During a hypo, adrenaline is released which leads to a release of sugar from the liver and makes the blood sugar rise with a time delay. To check this, a nightly check of your blood glucose values between 2 a.m. and 3 a.m. can help.