In line with the results from a previous meta-analysis that evaluated several studies on herpes zoster (HZ),1 the findings from a literature review by a group of researchers in France demonstrate that diabetes is a risk factor for HZ infection in adults.2
The causative agent of HZ, varicella zoster virus (VZV), is commonly known to cause chickenpox during childhood. The virus remains latent in trigeminal and dorsal root ganglia before it is reactivated – resulting in HZ.3 The most challenging complication of HZ is post-herpetic neuralgia (PHN) – persistent pain that occurs at healed HZ lesion areas.3 It may remain for several years affecting quality of life. The annual incidence of HZ has been reported at three to five cases per every 1,000 person-years.4,5 The incidence of HZ was also reported to be higher in patients with certain co-morbid conditions such as diabetes1 – which is known to be associated with infectious diseases.6
The literature review evaluated 16 studies to determine the role of diabetes as a risk factor for HZ.2 The selected studies were conducted at various sites across the world.
The risk of HZ was found to be significantly higher in patients with diabetes in 11 out of 16 studies,2 and the magnitude of the risk ranged from 1.06 to 2.38 (95% CI, 1.03–1.09, 2.04–2.78; p<0.05). The incidence of HZ among patients with diabetes was also reported to be higher in women and older population. Furthermore, diabetes also was found to be associated with PHN by several studies including a nationwide study in Taiwan (RR, 1.35; 95% CI, 1.25–1.47), Israel and the United States.2
Impairment of cell mediated immunity and innate immune responses that are present in patients with diabetes have been described to be possible causes of their susceptibility to reactivation of VZV.10,11 Prevention of HZ in these patients which includes HZ vaccination should be considered. Currently, the vaccines are recommended for individuals 50 years of age and older.12 Based on the current findings, vaccination may be particularly beneficial to patients with diabetes due to the higher risk of HZ compared with the general population.