Nocturnal Hypos and Insulin Pumps
Insulin pumps give more control of blood glucose levels over night and so they can help to reduce the chances of having an overnight hypo. However, a number of factors can mean night time hypos can still happen.
Read on to see how you can help to beat night time hypos with the help of blood glucose testing and your pump.
Insulin pumps and background insulin
One key advantage of insulin pumps is that you can change the rate of background insulin (basal insulin) that the pump delivers at any point.
This is advantage over injections. With injections, once you have given your background insulin dose you are stuck with having that dose being gradually absorbed over the day.
As well as allowing you to change the rate of your background insulin at any point, you can also program in different rates of insulin delivery at different times of day.
This can be helpful in preventing hypos. Read on to find out what to take into account when setting over night basal insulin rates.
It is quite common for people with diabetes to have periods of the night where sugar levels go lower than normal. If you know which point of the night you are tending to go low, you can program your insulin pump to deliver less insulin around that part of the night.
Unless you have access to a continuous glucose monitor, carrying out some blood glucose testing over night may be your best chance of finding out whether or when you are going low over night.
None of us like getting up to test blood glucose levels over night but it can be a very useful way to prevent lows over night.
Testing needn’t be done each night but a few tests at different times of night on different days may help to give you an idea of how your sugar levels are behaving when you’re sleeping.
Programming basal rates to prevent hypos
If you are experiencing hypos over night, or blood glucose testing during the night is showing that your sugar levels are getting too close for comfort to hypo range, you can set your insulin pump to deliver a lower rate of background insulin.
Some people may find that setting a lower rate over night may lead to higher than ideal results in the morning. This can sometimes be caused by what’s often called the dawn phenomenon, whereby the liver prepares the body for waking by releasing extra glucose into the blood.
To get around the problem of preventing low blood sugar levels over night but high blood glucose levels in the morning, you can program your pump so that it delivers a smaller rate of background insulin through the night and a higher rate just before waking.
Fine tuning your background insulin can be a bit of an art. Blood glucose testing and experience helps and your health team can also offer advice on how best to set up your background insulin over night.
Factors which can increase the risk of over night hypos
There are a few factors which can significantly raise the risk of hypos over night. It’s useful to be aware of these factors and it can also help to understand why they raise the risk of hypos.
If you have a more active day than normal, your muscles may still be refuelling when you go to sleep. When we exercise, our muscles take in glucose from the blood but will also make use of stored glucose from our muscles and liver.
After a good session of exercise, our muscles will replenish their glycogen (a stored form of glucose) stores. They will do this by taking in glucose from the blood, thus gradually lowering blood glucose levels.
This can be a problem over night as it can raise the risk of hypos. To prevent hypos from occurring over night, you may wish to decrease your rate of background insulin over night following a significant period of exercise in the day.
Alcohol can also affect blood glucose levels quite dramatically. Many of know that alcohol has an effect on the liver but its knock on effect on blood sugar levels is slightly less well known.
The liver helps to release a steady drip of glucose into our blood. This is one reason why we need to take background insulin through the day. However, when we have alcohol, the alcohol can prevent the liver from releasing glucose into the blood and this can mean that we have an imbalance of too much insulin and this raises the risk of hypos happening.
After having alcohol, you may need to decrease your basal insulin to prevent hypos occurring.
Following a period of illness
When we are ill, the body’s immune system steps up a gear and this often results in a decreased sensitivity to insulin. What this means is that often during illness, our blood glucose levels become higher through the day. This can mean needing to take higher doses of insulin than normal. You may find that the rise in blood glucose sometimes occurs before the symptoms of illness have appeared.
Setting your over night basal insulin at an appropriate rate can sometimes be a challenge. Your health team should be able to advise you on picking a safe rate.
Once your immune system starts to beat the infection, your blood glucose levels can come back to normal. If you have been on a higher dose of insulin over night, the improved sensitivity to insulin can raise the risk of hypos occurring.
To minimise the risk of hypos, you may allow your blood glucose levels to be a bit higher than usual over night during the time of illness so that when your insulin sensitivity returns, the risk of having a hypo will be lower.
Another way to reduce the likelihood of a hypo over night is to wake up in the middle of the night to test your blood glucose. It’s not an ideal situation but may be preferable to risking going too low over night.
Change in weather
A number of people find that their blood glucose levels experience changes when a period of warmer or cooler weather begins.
For some people, blood glucose levels get lower during warmer weather whereas for others the opposite may apply. You will likely need to rely on experience to find out how your own body responds to changes in climate.
Predicting a change in blood glucose levels can be as difficult as predicting a change in weather itself so often the best we can do is to react quickly enough.
If you experience a trend of lower blood glucose levels in the morning or over night for no other reason, it could be related to a change in climate. As with any trend of low blood glucose levels over night, it’s recommended to either lower your basal insulin over night or to take a snack before bed.
Should I adjust my basal rate after exercise?
Following a period of exercise, your muscles will take in glucose from your blood to replace the glycogen (a form of glucose) they will have used during exercise. This often means that people with type 1 diabetes have a higher tendency to experience hypos up to 48 hours after exercise.
The advantage of being on an insulin pump is that you can switch to a lower basal rate than normal to reduce the chances of going hypo.
Your health can help you to decide by how much and for how long to reduce your basal dose for. With experience, you can tailor changes to your basal rate following different exercises and different durations of exercise.