(LifeWire) - When suffering from a cold, flu, or just about any other illness, the body is placed under tremendous physical stress in an effort to fight the infection. As part of the infection-fighting process, the body produces more glucose in the form of glucagon, a hormone that raises blood sugar levels.
For diabetics, this extra glucose in the bloodstream can lead to dangerously high blood sugar levels. Therefore, it is important to continue taking regularly prescribed oral medications (for type 2 diabetes) and insulin (for type 1 or type 2 diabetes) when sick and to regularly check blood sugar levels to assess whether more insulin is necessary.
How Often Should Blood Sugar Levels Be Checked During Illness?
Blood sugar levels may fluctuate dramatically during an illness, requiring frequent checks throughout the day, as often as hourly.
When blood sugar levels are high -- above 300 mg/dL -- it is also necessary to check for ketones in the blood or urine, which is a byproduct resulting from the body using fats as an energy source. The presence of ketones indicates diabetic ketoacidosis (DKA), which is a dangerous build-up of acid in the body due to high blood sugars.
People with type 2 diabetes may develop a hyperosmolar hyperglycemic state (HHS), which is a life-threatening condition similar to DKA, except that there are no ketones present. Infection is the most common cause of DKA with type 1 diabetics in 30% to 40% of cases and of HHS with type 2 diabetics in 32% to 60% of cases.
How Does Illness-Related Appetite Loss Affect Blood Sugar Levels?
Normally the body is largely dependent on food to provide glucose to the bloodstream. Going without food for prolonged periods, particularly while continuing to treat diabetes with oral medications and/or insulin, can lead to dangerously low blood sugar levels (hypoglycemia) causing symptoms such as palpitations, shakiness, hunger, confusion, and even convulsions and coma.
However, during illness or other stress, the body's own immune system triggers glucose production whether or not blood glucose is boosted by food intake. In fact, blood sugar levels, and therefore insulin requirements, are typically higher on sick days without food than on regular days with normal meals.
Even if solid food is unpalatable, it is important to maintain an adequate intake of fluids to prevent dehydration. It is helpful to drink fluids containing carbohydrates and salt to maintain the electrolyte balance in the body. Dehydration and electrolyte imbalance can contribute to excess acid in the bloodstream with dangerously high blood glucose levels. Dehydration often requires in-hospital treatment with intravenous fluids.
What If It's Impossible to Keep Food Down?
Sometimes illness leads to nausea and an inability to keep any food or medications down. While it may be tempting to skip oral medications in this case, it is important to take them to treat the high blood sugar levels that naturally occur when ill, and also to dose the insulin accordingly, even if illness prevents eating.
While fighting an illness, most people with type 1 diabetes will require additional short-acting insulin, along with typical doses. Similarly, people with type 2 diabetes who manage the disease entirely by diet and oral medications may require short-acting insulin during the course of an illness to treat high blood sugar levels.
Are Over-the-Counter Medications Safe to Take?
Often when people are sick, they look for remedies to treat various symptoms, such as a cough or fever. While these nonprescription medications are typically fine for people with diabetes, it is important to remember that they can affect blood sugar levels and could potentially interact with diabetes medications. For example, cough syrup generally contains sugar, which raises blood sugars. Some antibiotics can interact with oral diabetes medications and result in lower blood sugar levels.
It is important to talk with the diabetes care team before taking any additional prescription or nonprescription medication to determine what, if any, changes to the diabetes regimen will be necessary.
When Should a Doctor Be Consulted?
Before illness arises, it is helpful to have a glucose management plan in place for sick days. The plans may vary over time, as diabetes medications and other factors change during the course of diabetes care. In addition, the type and amount of over-the-counter medications may vary with changing glucose management plans. Whether sick or well, it is always important to talk with the diabetes care team before taking any over-the-counter or prescription medications or supplements.
During illness, it is important to share a variety of information with the diabetes care team, including symptoms -- such as nausea, vomiting, diarrhea, or fever -- amount of insulin given, food and fluid intake, heart rate, breathing rate, and current body weight. This information will help healthcare providers advise patients on how to manage their blood sugar levels and other symptoms during the illness with a goal of preventing dehydration and the development of dangerous hyperglycemia, DKA, or HHS.
Sources:American Diabetes Association. "Position Statement: Hyperglycemic Crises in Diabetes." Diabetes Care (2004) 27(Suppl 1): S94-S102. 16 Nov. 2007 . <http://care.diabetesjournals.org/cgi/content/full/27/suppl_1/s94>
"When You're Sick." Diabetes.org. American Diabetes Association. 15 Nov. 2007. <http://diabetes.org/pre-diabetes/when-you're-sick.jsp>
Kitabchi, Abbas E. and Haleh Haerian. "Epidemiology and Pathogenesis of Diabetic Ketoacidosis and Hyperosmolar Hyperglycemic State." UpToDate.com 2007. UpToDate. 16 Nov. 2007 (subscription) .
McCulloch, David K. "Illustrative Cases of Intensive Insulin Therapy in Special Situations." UpToDate.com 2007. UpToDate. 15 Nov. 2007 .