If the blood sugar level becomes higher than 14–15 mmol/l for no apparent reason, it is important to keep in mind insulin deficiency and the risk of diabetic ketoacidosis (DKA). To be safe, ketone levels should be checked if there is no clear reason for the increase in blood sugar, such as being late with or forgetting a mealtime injection or snacking without dosing insulin.
Sudden diseases, especially fever, increase the need for insulin. If the blood sugar level rises above 14–15 mmol/l when sick, ketone levels should be checked. This should be done even if the blood sugar is not that high but general condition has clearly become worse or there are symptoms of DKA.
Those with tpye 1 diabetes or another form of insulin-dependent diabetes, instructions on how to check the blood sugar and dose insulin when ill as well as how to use a rapid meter to check the blood ketone level and what to do about the result will be given by the diabetes care provider.
Checking the blood ketone level is especially important for a person with insulin-dependent diabetes who uses SGLT2 inhibitors because, in that case, blood sugar is not usually as high as normal during DKA.
Instructions regarding the risk situations related to DKA and what to do about them are discussed in the start of insulin pump therapy. A person starting pump therapy must have clear written instructions on what to do in case of a high blood sugar.