Virus Is Risk Factor for Type 2 Diabetes in Elderly
Scientists appear to have uncovered another risk factor for type 2 diabetes, and this time it is one that seems to affect the elderly. That risk factor is cytomegalovirus (CMV), a virus that can lie dormant for decades before springing into action.
You can have the virus and not know it
Cytomegalovirus is a member of the same family occupied by herpes simplex virus 1 and 2, varicella zoster virus, and human herpes virus. The Centers for Disease Control and Prevention (CDC) has estimated that 50% to 80% of individuals in the United States have had a CMV infection by age 40 years, while some experts estimate the rate is even higher.
The life cycle of CMV typically begins as an asymptomatic infection, and most healthy people don't even know they have the virus. When symptoms do occur they are usually similar to mononucleosis or various other illnesses (e.g., tiredness, swollen glands, fever, sore throat, headache), therefore individuals typically don't know they've been infected. The virus then hides (goes dormant) and usually stays that way throughout a person's lifetimes.
Sometimes, however, it reactivates, most often in people who have a weakened immune system associated with disease or drug treatment. That's when the disease can cause serious illness, and as indicated in this new study, it may trigger type 2 diabetes in the elderly.
Investigators from Leiden University Medical Centre and University of Tubingen Medical School used data from the Leiden 85-plus Study and compared glucose regulation with antibodies to CMV in more than 500 participants. They discovered that having CMV was associated with type 2 diabetes.
More specifically, individuals who tested positive for CMV were more likely to have type 2 diabetes (17.2%) than were people who did not test positive (7.9%). Patients with CMV also had a higher level of hemoglobin A1c and non-fasting glucose levels.
Exactly why CMV may initiate type 2 diabetes in the elderly is not clear, although the researchers suggested that the virus could either directly attack the pancreatic cells (beta cells are responsible for making insulin) or indirectly prompt the immune system to attack the pancreas.
The researchers noted that their finding "leads to the hypothesis that CMV seropositivity [showing positive reactions to blood tests for a disease] may facilitate the onset of type 2 diabetes in the long term."
Theirs is the first study to show that the virus is "positively independently associated with indicators of glucose regulation" and warrants further research to further clarify the role of CMV infection in type 2 diabetes in the elderly.
Centers for Disease Control and Prevention
Chen S et al. Cytomegalovirus seropositivity is associated with glucose regulation in the oldest old. Results from the Leiden 85-plus study. Immunity & Ageing 2012 Aug 28. 9:18
Image: Wikimedia Commons