During sick days, blood sugar should be initially measured at least every 2-4 hours or a glucose sensor should be used. During illness, an appropriate blood sugar level can be around 8–10 mmol/l. If blood sugar exceeds 10 mmol/l, additional doses of rapid-acting insulin are taken.
Additional doses of rapid-acting insulin are administered based on blood sugar every 2-4 hours, in addition to what is injected for eaten and drunk carbohydrates. One extra unit of rapid-acting insulin generally lowers blood sugar by about 1–4 mmol/l, depending on individual insulin sensitivity. You can read more about determining individual insulin sensitivity (ISF) in the Diabeteshub's article "Use of correction insulin."
During sick days, counterregulatory hormones reduce the effectiveness of injected insulin, and the need for corrective insulin may be higher than usual. If blood sugar continues to rise regardless of correction doses, the amount of corrective insulin should be increased by 30–50% from the usual dose while also consuming plenty of mineral water.
Monitor ketones
For sick days, it would be good to have strips available that measure blood ketones. Ketones increase if there is too little insulin. Based on the measurement results, insulin doses and hydration are increased. An excessive accumulation of ketones can lead to diabetic ketoacidosis (DKA).
Adjust the basal insulin dose if necessary if the illness is prolonged
A mild fever lasting a few days is generally managed with additional doses of rapid-acting insulin. If the illness is prolonged, there may also be a need to increase the dosage of basal insulin. Long-acting basal insulin may need to be increased by up to 25% for each degree above 37.5 ºC measured from the armpit in the morning. If basal insulin is increased, the need for additional rapid-acting insulin is smaller, but additional doses may still be required. Blood sugar should continue to be monitored every 2-4 hours despite increases in insulin doses.