For people with diabetes, influenza is more than just a seasonal nuisance. According to the Centers for Disease Control and Prevention, you are 3 times more likely to require hospitalization, develop a serious complication or die from flu if you have diabetes. Leonard Thompson, the first person to be treated with insulin for diabetes, died in 1935 from an influenza-related complication. A decade later, flu vaccines became widely available for the first time.
Doctors have long recognized that people with diabetes are more susceptible to infections, and scientists have demonstrated a number of immune deficits in people with diabetes. Decreased white blood cell activity, poor antibody function and a reduced capacity for recognizing and eliminating bacteria are among the immune defects identified in people with diabetes. Notably, bacterial pneumonia is the principal cause of death in people infected with flu, and people with diabetes are particularly likely to die from this complication.
Increased Risk of Heart Attack
Diabetes is a well-established risk factor for cardiovascular disease, and people with diabetes may have underlying heart disease that does not cause symptoms. An October 2009 review in “The Lancet Infectious Diseases” showed that people are more susceptible to heart attacks during a bout of flu, even if they do not have diabetes. This finding becomes more compelling in light of a 2- to 4-fold higher risk for cardiovascular disease in people with diabetes. Furthermore, people who have cardiovascular disease, as many people with diabetes do, are more susceptible to severe viral pneumonia due to influenza.
High Blood Glucose
Hyperglycemia, or high blood glucose, is the hallmark of diabetes, and a principal goal of diabetes management is to control blood glucose levels. Infections, including influenza, are a common cause of hyperglycemia, even in people whose diabetes is normally well controlled. The reasons your blood glucose rises during an illness are not entirely clear, but increases in stress hormones, such as cortisol, epinephrine and growth hormone, probably play a role.
If you are not able to compensate for higher blood glucose with extra insulin or oral medications, severe complications, such as diabetic ketoacidosis or hyperglycemic hyperosmolar syndrome, may result. These conditions are characterized by hyperglycemia, dehydration, deterioration in neurologic function and shock. If not promptly treated, DKA and HHS can both be fatal.
Influenza is a preventable disease, and immunization against flu is highly recommended for people with diabetes. Each year’s flu virus is typically different from the preceding one, so annual vaccination is necessary to get full protection. Two types of influenza vaccine -- an inactivated, injectable form and a nasal vaccine containing a live, weakened virus -- are currently available. Due to the immune impairment in people with diabetes, only the injectable, inactivated vaccine is currently recommended for people with diabetes. The American Diabetes Association also recommends pneumococcal vaccination for all people with diabetes over 2 years old. This vaccine will protect you from some of the most common bacterial causes of pneumonia.