Zoning in on Sick Day Management: Practical Tips, Strategies, and Advice
Pediatric endocrinologist Dr. Fran Kaufman shares her best tips for managing illness and diabetes: make a sick day plan, have supplies on hand, log your data, modify your insulin doses, and call your healthcare team.
Everyone with diabetes who takes insulin needs to have a sick day plan. This is something you develop with your healthcare provider to help you manage 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.
Why it’s important to have a sick day plan
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 that, when coupled with high glucose levels, can lead to diabetic ketoacidosis (DKA), a very serious condition. It’s a good idea to have some form of ketone testing available at home – blood ketone meters are available online or at local pharmacies.
The purpose of your sick day plan is to try to keep your glucose levels in a safe range to avoid dehydration and prevent ketones from rising to a dangerous level. When you get sick, you should contact your healthcare team, describe your symptoms, and share numbers that you have collected in your sick day log (more on this below). This will help your healthcare team determine if they want to evaluate you or do further testing.
It is possible that no matter what you do, you might need to go to an emergency department or be hospitalized – but acting quickly, obtaining the right data, and doing your best to manage your glucose and hydration will minimize risks.
How illnesses affect your metabolism
So what illnesses are we talking about? It turns out just about any common bacterial or viral infection – such as the flu (influenza), a cold (upper respiratory virus), tonsillitis, strep throat, an ear infection, stomach flu (gastroenteritis), a bladder infection, and even a skin infection such as an abscess – can interfere with your diabetes management.
Although the pandemic ended in May 2023, the virus that causes COVID-19 continues to circulate and remains a particular concern for people with diabetes. A COVID-19 infection can lead to very high glucose and ketone levels, putting someone at risk for DKA.
When you get sick, your body needs energy to fight the infection and repair damaged tissue. Infections, particularly those that lead to vomiting, diarrhea, fever, and dehydration, cause your body to release certain hormones (called stress or counterregulatory hormones) that tell your liver to release stored glucose and your fat cells to release free fatty acids that form ketones.
How blood sugar management changes during an illness
In a person without diabetes, the body releases more insulin to control the rise in glucose and ketones; if you have diabetes, you have to take additional insulin to manage the high glucose and ketone levels. When you are sick, you want to keep your sugar levels between 100-180 mg/dL. Blood sugars below 180 mg/dL will prevent excess urination that can dehydrate your body. Staying above 100 mg/dL helps keep you from dipping too low and risking severe hypoglycemia.
If you are taking multiple daily injections and your glucose level is above 180 mg/dL, you need to consider increasing basal insulin doses, using either an increase in basal insulin, or giving repeated corrections of bolus insulin with a syringe or pen. Usually, correction doses should not be given more often than every two to three hours to avoid “stacking” insulin, which could lead to low blood sugar. By having a plan for illnesses that starts your modified care early and keeping in touch with your healthcare team, you are more likely to keep your glucose values in the 100-180 mg/dL range. If you are using an automated insulin delivery (AID) system, it should eliminate a lot of guesswork around dosing and make things easier by having the system adjust insulin doses based on continuous glucose monitoring (CGM) data.
However, you also have to be concerned about hypoglycemia. Low sugar occurs, particularly in children and older adults, if the illness affects calorie and carbohydrate intake by decreasing appetite or by causing vomiting or diarrhea. Although low glucose is usually considered to be less than 70 mg/dL, during illness, there is concern if glucose levels are below 100 mg/dL.
If your infection or illness leads to low glucose levels, reducing basal insulin and not taking bolus (mealtime) insulin doses should be considered. Even if suspension of bolus insulin is required, you should not delay taking the next dose of basal insulin for more than 60 minutes, as this could increase your risk of developing ketones. Start sipping a sugar-containing drink, one tablespoon at a time.
If hypoglycemia continues and you cannot make it better by ingesting sugar, consider the administration of low-dose glucagon. Low-dose glucagon can increase glucose level by 50-200 mg/dL in 30 minutes. Keep in mind that low-dose glucagon without severe hypoglycemia is considered off-label (i.e. not officially approved by the FDA). To learn about whether low-dose glucagon is right for you, and at what dose, talk with your healthcare team.
What to watch out for when you’re sick
To follow what is happening in your body, it helps to start a log of your glucose levels, ketones, fluid intake, and insulin doses. It should show improvement from one time period to the next. The log below shows only two days because you should be better after 24 hours and on the mend after 48 hours.
Note that the biggest concern is vomiting; if you vomit more than twice in a time period or across two time periods (or are generally not getting better), call your healthcare team. 
Here’s how (and why) to keep track of these important numbers:
1. Glucose levels
If you are using a blood glucose meter, check your blood sugar levels every one to two hours. You may have to change this and check your glucose every 30 minutes if your levels are changing quickly. If you are using a CGM, check trend data every 10-15 minutes. Watch for rapid changes by looking at numbers and arrows. The goal is to keep your glucose between 100-180 mg/dL without wide swings in values.
2. Ketone levels
Ketones should be measured with a fingerstick and a special ketone meter. The readings for blood ketones are more accurate than urine ketones and range from 0.0 to 3.0 mmol/L or greater. Blood ketone levels below 0.6 mmol/L are considered normal. Between 0.6 and 1.5 mmol/L is high and shows that your fat has broken down to form excess ketones. This puts you at risk of DKA if glucose levels are also elevated. Ketone levels above 1.5 mmol/L are serious, and you should contact your healthcare professional. Ketone levels above 3.0 mmol/L require immediate medical attention.
Ketones can also be measured using a urine ketone strip. A small patch on the strip changes color depending on your level of ketones, representing negative, small, moderate, large, and very large levels of ketones. Moderate, large, and very large levels are of concern.
Signs of elevated ketones:
- Nausea and vomiting (which may also be present because of the infection)
- Shortness of breath and labored breathing (your body is trying to eliminate the ketones through your breath, so you can also smell them; they make your breath smell fruity)
- Weakness
- Altered level of consciousness and trouble staying awake (this is most concerning; call your healthcare professional immediately if this is happening)
Ketones should be tested at the onset of an illness and then every four hours. If ketone and glucose levels are both elevated, your healthcare team might advise you to increase correction insulin doses further by an additional 10-15%. If ketone levels are high and glucose levels are not high (less than 150 mg/dL), oral glucose and some insulin – reduced by about 50% – should help clear your ketones. Drinking water will also help reduce ketones as they are removed in the urine.
3. Temperature
A high fever can help indicate the severity of your illness, particularly if it is persistent. Use the log sheet to document any medications you take to lower your fever and report this to your healthcare team.
4. Fluid intake with and without sugar
Consuming liquids is critical if there is a risk of dehydration. Fluids with sugar should be taken if glucose levels are between 100-150 mg/dL, and fluids without sugar should be taken if glucose levels are between 150-180 mg/dL. If you have vomited, wait 30-60 minutes before trying to drink, and then start with teaspoons of water or ice chips, progressing to tablespoons and ounces. The goal is to retain four to six ounces of fluids (or two to four ounces for young children) every 30-60 minutes until you can drink without risk of vomiting and as your thirst dictates. Food is much less important after vomiting – don’t try to eat food until you are on the mend.
5. Urination
Noting the frequency and amount (small, medium, or large) is important to understand the ongoing risk of dehydration. As glucose levels reach the target of 100-180 mg/dL, you should see a decrease in both frequency and amount of urination, as well as less dehydration.
6. Vomiting, diarrhea, and dehydration
Vomiting and diarrhea can lead to dehydration. The signs of dehydration include dry mouth, sunken eyes, weakness, loose skin, rapid heart rate, and low blood pressure. Vomiting especially is of great concern because it occurs not only from the illness, but also as a result of DKA. That’s why vomiting that occurs throughout one time period or that spans two time periods in your log means it is time to call your healthcare provider. However, if you feel weak after vomiting only once or twice, it is always better to call earlier than later.
7. Insulin amount and timing
One of the most important things to remember is that during an illness, you still need to take insulin. Even if you are not eating or drinking at the beginning, you need to have insulin in your body. Insulin allows sugar to enter your body’s cells to be used for energy, and you need more energy to fight off an illness. Insulin also reduces ketone formation and stops excess urination by lowering glucose levels.
If you use multiple insulin injections and have high blood glucose, you might need 25-50% more insulin than you usually take, due to insulin resistance created by the extra stress or counterregulatory hormones in your body. If you have low glucose, you might need to take 25-50% less insulin than you usually take, but you still need some basal or background insulin on board.
8. Medications
At the beginning of an illness, you should consider calling your healthcare team to determine if you should avoid taking any of your routine medications while sick. This includes glucose-lowering pills or injections, such as SGLT-2 and GLP-1 drugs, or medications for blood pressure and cholesterol. In addition, it is important to write down any medications you take (name, dosage, time) to treat fever, vomiting, diarrhea, or other symptoms of your illness. Anti-vomiting medications may be helpful, but should only be taken after discussing with your healthcare professional.
The bottom line
It’s important to create a sick day plan before you become ill and to assemble everything that you might need beforehand. Along with contact info for your healthcare team, your sick day plan should include a log sheet to record your health data and symptoms, as well as necessary medical supplies. These include supplies to measure glucose, a way to measure ketones, a thermometer, sugar-containing fluids, glucagon, extra-rapid (or short) acting insulin, and medication to treat fever. Discuss with your healthcare team whether you should have medication for diarrhea and vomiting on hand as well.
When you become sick, measure your blood sugar more regularly and modify your insulin doses as necessary. Even if you are not eating, you still need some insulin in your body. In addition to contacting your healthcare team, it’s important if you have the option to let someone help you while you are ill – it may be a big job and you don’t have to do it alone.
Learn more about navigating illnesses with diabetes here: