It’s that time of year again: flu season. With September right around the corner, you should be preparing to get your annual vaccine against influenza or, as it is usually called, the flu.
The flu is a highly contagious respiratory illness that is caused by a virus. Symptoms of the flu include cough, sore throat, runny or stuffy nose, body aches, headache, and fatigue, all of which can range from mild to severe. Often the flu is accompanied by fever, with its usual symptoms of alternating chills and uncomfortable warmth. While most flu symptoms involve the respiratory tract, vomiting and diarrhea can also occur; these symptoms are more common in children than adults.
Most people recover from the flu within a few days to less than two weeks. However, some people develop serious and sometimes life-threatening complications from the flu. Such complications may include secondary infections such as pneumonia, bronchitis, and ear or sinus infections, or the worsening of a preexisting chronic condition such as asthma or congestive heart failure.
Diabetes and the flu
If you have diabetes, you are considered at high risk for getting the flu and for developing complications, even if your blood glucose is well controlled. This is because diabetes can impair your immune system’s ability to fight off an attacking virus such as the flu. Then, once you catch the flu, your body may respond negatively in several ways to the stress of being sick. During times of stress, the body releases stress hormones such as epinephrine (adrenaline) and cortisol, which raise your heart rate and blood pressure. Epinephrine — along with glucagon, a hormone produced by alpha cells in the pancreas — also causes the liver to release stored glucose, leading to elevated blood glucose levels in many people with diabetes.
Being ill can also make you feel less like eating and disrupt your regular meal plan, which can make blood glucose levels even more erratic. It is thus possible for the flu to lead to acute diabetes complications such as ketoacidosis — a life-threatening condition brought about by a lack of insulin, and marked by extremely high blood glucose and often a fruity odor in the breath — or to dangerous hypoglycemia (low blood glucose), depending on the balance of hormones and food intake during the illness.
The best defense against the flu is prevention, which means getting vaccinated against the virus. The Centers for Disease Control and Prevention (CDC) recommends that people at high risk for the flu get a flu shot to help protect themselves and those around them (see “Who Should Get a Flu Shot?”). The vaccine should be taken once a year, ideally in September or October or as soon as it becomes available to the public. Once you get your flu shot, it will take about two weeks for your body to develop antibodies, which are proteins used by your immune system to identify and destroy the viruses that cause the flu. If you miss the vaccine in the early fall, keep in mind that flu season generally peaks in the winter months, so you can still benefit from getting a flu shot later in the year.
The vaccine for flu season 2012–2013 is made up of three inactive viruses, selected by experts around the world based on research into which types of flu viruses are likely to be the most common. This year’s viruses are an A/California/7/2009 (H1N1)-like virus; an A/Victoria/361/2011 (H3N2)-like virus; and a B/Wisconsin/1/2010-like virus. While you don’t need to remember the names of these viruses, it is important to note that the flu vaccine protects only against selected strains; it does not provide 100% protection against the flu, because other, less common flu viruses may still be spread during the season.