A new study reveals that A new study published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]) finds that two common herpesviruses may contribute to impaired glucose metabolism and increase the risk of developing type 2 diabetes. 2 (T2D) among infected people. The research was conducted by Dr. Tim Woelfle at Ludwig-Maximilians and Helmholtz University Munich, Germany, and his colleagues.
Herpesviruses are one of the most prevalent viruses in humans, with eight types currently known: herpes simplex virus (HSV) 1 and 2, varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus ( CMV) and human herpesvirus. (HHV) 6, 7 and 8.
All of them cause lifelong latent infections in their hosts after an initial primary infection, usually mild or asymptomatic.
T2D is one of the most widespread and important metabolic diseases, with an estimated 9.3% of the global population suffering from the condition as of 2019, exerting a high mortality burden primarily due to resulting cardiovascular disease. There are many known behavioral, environmental, and genetic risk factors for T2D, but until recently, only viruses have been proposed to play a role in the development of type 1 diabetes, in which the pancreas stops producing enough insulin. .
An individual can be diagnosed with prediabetes when they have impaired fasting glucose (IFG) or impaired glucose tolerance (IGT). Previous studies have found that the incidence rate of T2D is much higher in people with prediabetes (7.6% per person-year) than among people with normal glucose tolerance (0.6% per person-year).
The research was based on health data from 1967 subjects in the population-based health research platform KORA (Cooperative for Health Research in the Augsburg Region) in southern Germany. Participants underwent detailed health examinations at baseline (2006-2008) and follow-up (2013-2014), including testing for the presence of human herpesviruses, oral glucose tolerance tests (OGTT), and measurement of Glycated hemoglobin (HbA1c) (a measure of blood sugar control over the previous 3 months).
The study group had a median age of 54 years at baseline, 962 (49%) were men, and 999 (51%) were women. The incidence analysis for the development of (pre)diabetes used data from those 1,257 participants with normal glucose tolerance at baseline (median age 49 years, 42% men and 58% women [528 and 729 individuals, respectively]). .
Participants without a prior diagnosis of T2D underwent a standard OGTT with diabetes status assigned using thresholds recommended by the American Diabetes Association. Further analysis of blood samples was performed to detect the presence of antibodies against 7 of the 8 known human herpesviruses, which would indicate the presence of both primary and latent infections.
The following variables known to be associated with diabetes risk were also assessed at baseline: sex, age, BMI, years of education, ever smoking status (yes/no), leisure-time physical activity ( active/inactive), parental diabetes (yes/no) and hypertension (yes/no, defined as blood pressure greater than 140/90 mmHg).
The prevalence of prediabetes (IFG and IGT) was 27.5% at baseline and 36.2% during follow-up, while T2D was present in 8.5% of participants at baseline and 14.6%. % during follow-up. Of the 1,257 volunteers with normal glucose tolerance at baseline, 364 developed prediabetes and 17 developed T2D during the median follow-up period of 6.5 years. The authors found that age, BMI, smoking, and years of education were all associated with an individual’s risk of developing prediabetes and T2D.
Blood tests at the start of the study found that EBV was the most prevalent herpesvirus with 98% of the sample group being seropositive, followed by HSV1 (88%), HHV7 (85%), VZV (79%), CMV ( 46%). ), HHV6 (39%) and HSV2 (11%). Participants were seropositive for an average of 4.4 herpesviruses at baseline and 4.7 at follow-up. About a third (34%) tested positive for more viruses at the end of the follow-up period, 54% had the same number, and only 12% tested positive for fewer viruses than at the beginning.
Although herpesviruses are persistent in their hosts, they may not always be detected by antibodies in the blood.
Infection usually occurs in early childhood, but can occur in adulthood, so while the seroconversions observed may be new cases, they are more likely due to the immune response to a previously undetected virus. Likewise, a person who loses seropositivity cannot be considered free of the virus and is much more likely to be in a state of undetectable latency.
Of the seven herpesviruses examined, HSV2 and CMV were associated with the incidence of (pre)diabetes among people with normal glucose tolerance at baseline, which were independent of other risk factors. People with HSV2 were 59% more likely to develop (pre)diabetes than those who were seronegative, while CMV infection was associated with a 33% increase in the incidence of (pre)diabetes.
The study found that both HSV2 and CMV contributed consistently and complementary to the development of (pre)diabetes , even after taking into account sex, age, BMI, education, smoking, physical activity, parental diabetes, hypertension, lipid levels, insulin resistance and fasting. glucose. HSV2 was also found to be associated with HbA1c levels, independently of other confounding factors and the prevalence of (pre)diabetes itself.
The authors say: "Our study suggested that while the incidence of (pre)diabetes was mainly explained by age, BMI, cholesterol and fasting glucose, both HSV2 and CMV added additional complementary risk information, despite the high viral prevalence and coexistence."
The mechanisms by which these viruses could contribute to the development of (pre)diabetes remain to be discovered. Both HSV2 and CMV cause chronic infections that could modulate the immune system by stimulating or suppressing its activity, which in turn can influence the function of the endocrine (hormonal) system. Previous research has established that there are still unknown causes of T2D in addition to those involving the development of metabolic syndrome.
The authors conclude: "These results highlight the link between viruses and (pre)diabetes, and the need for more research evaluating public health viral prevention strategies, possibly including the development of effective vaccines against herpesviruses."
