For folks taking insulin, Diabetes Daily has a good article by endocrinologist Dr Francine Kaufman. An excerpt:
Everyone with diabetes who takes insulin needs to have a sick day plan. This is something you develop with your healthcare professional to help you manage the high and low sugar levels that can be associated with an illness. The following advice applies to people with type 1 diabetes and people with type 2 diabetes who take insulin – the advice may be different if you have type 2 diabetes and do not take insulin.
Click to jump down to a section:
What happens when you are sick?
Track of your important numbers in a sick log
Vomiting, diarrhea, and dehydration
Insulin, amount and time
Key messages from Dr. Kaufman
When you get sick, you are at risk of becoming dehydrated from poor intake or from excessive loss of fluids due to nausea, vomiting, diarrhea, and fever (your body may lose more water when you have a high temperature). In addition, dehydration is common in diabetes because high glucose levels (above 180-200 mg/dL) cause sugar to enter your urine, dragging an excess amount of fluid with it. Illness also puts you at risk of developing ketones, which when coupled with high glucose levels can lead to diabetic ketoacidosis (DKA), a very serious condition. How do you know if you have ketones? Good question, click here!
The purpose of your sick day plan is to try to keep your glucose levels in a safe range – to avoid dehydration and to prevent ketones from rising to a dangerous level.
Source: Zoning in on Sick Day Management: Practical Tips, Strategies, and Advice – Diabetes Daily