Hypos overnight are a problem for several reasons:
- They are harder to detect than hypos during the day.
- If they occur frequently they can affect your ability to detect hypos early.
- They tend to cause the glucose to rise in the morning and after breakfast.
You can’t really exclude overnight hypos unless you have checked your blood glucose at 3am on a few occasions – your glucose level can be normal on waking, even if it was low earlier. We don’t recommend you do this routinely, but it is certainly worth considering every now and then.
What causes overnight hypoglycaemia?
- Too much background insulin.
- Prolonged exercise the day before (without appropriate carbohydrate replacement or reduction in insulin dose).
- Drinking alcohol the night before (alcohol stops the liver making glucose – which normally maintains the blood glucose overnight).
How to solve this problem
- If you’re going to bed with a normal glucose and it is consistently dropping overnight – you need less background insulin (consider a 10% reduction in dose).
- After prolonged exercise you may need to adjust your background insulin down. This is easier to do if you are on twice daily background insulin (see Step 3).
- Consider a reduced dose of background insulin on evenings where significant amounts of alcohol are consumed (and ensure you have had a carbohydrate snack before bed).