A new study reveals that infection with the herpes virus

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A new study published in Diabetology (the journal of the European Association for the Study of Diabetes [EASD]) finds that two common herpes viruses may contribute to impaired glucose metabolism and increase the risk of developing type 2 diabetes (T2DM) in infected individuals. The research was led by Dr. Tim Woelfle of Ludwig-Maximilians University and Helmholtz Munich, Germany, and his colleagues.

Herpes viruses are one of the most common 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 herpes viruses. (HHV) 6, 7 and 8. All cause lifelong latent infections in their hosts after an initial primary infection, which is usually mild or asymptomatic.

T2DM is one of the most prevalent and important metabolic diseases with around 9.3% of the world’s population affected by the disease in 2019, exerting a high mortality burden mainly due to the resulting cardiovascular diseases. There are many known behavioral, environmental and genetic risk factors for T2D, but until recently viruses had only been proposed to play a role in the development of type 1 diabetes, in which the pancreas stops functioning. produce enough insulin.

An individual can be diagnosed as having prediabetes when they exhibit impaired fasting blood glucose (IFG) or impaired glucose tolerance (IGT). Previous studies have shown that the incidence rate of T2D is much higher in people with prediabetes (7.6% per person-year) than in people with normal glucose tolerance (0.6% per person -year)

The research was based on health data from 1,967 subjects from the population-based health research platform KORA (Cooperative Health Research in the Augsburg Region) in southern Germany. Participants underwent extensive health screenings at baseline (2006-2008) and follow-up (2013-2014), which included testing for the presence of human herpesviruses, oral glucose tolerance tests (OGTT), and measurement glycated hemoglobin (HbA1 C) (a measure of blood sugar control over the previous 3 months).

The study group had a median age of 54 at baseline, 962 (49%) were male and 999 (51%) were female. The analysis of the incidence of developing (pre)diabetes used data from 1,257 participants with normal glucose tolerance at baseline (median age: 49 years, 42% male and 58% female [528 and 729 individuals, respectively]).

Participants without a prior diagnosis of T2DM underwent standard OGTT with diabetes status assigned using cutoffs recommended by the American Diabetes Association. Further blood sample testing was done to detect the presence of antibodies against 7 of the 8 known human herpes viruses, which would indicate the presence of primary and latent infections. The following variables known to be associated with diabetes risk were also assessed at baseline: gender, age, BMI, years of education, smoking status (yes/no), leisure-time physical activity (active/inactive), diabetes parental (yes/no) and hypertension (yes/no, defined as blood pressure above 140/90 mmHg).

The prevalence of prediabetes (IFG and IGT) was 27.5% at baseline and 36.2% at follow-up, while T2D was present in 8.5% of participants at baseline and 14.6% at follow-up. Of the 1257 volunteers with normal glucose tolerance at baseline, 364 developed prediabetes and 17 developed T2DM during the average follow-up period of 6.5 years. The authors found that age, BMI, smoking and years of education were all associated with individual risk of developing both prediabetes and T2D.

Blood tests at the start of the study revealed that EBV was the most common herpesvirus with 98% of the sample group 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 herpes virus 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 start. While herpes viruses 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 later in life. Thus, although the observed seroconversions may be new cases, they are more likely to be due to the immune response to a previously undetected virus. Similarly, a person who loses their HIV status cannot be considered free of the virus and is much more likely to be in an undetectable state of latency.

Of the seven herpes viruses examined, HSV2 and CMV were associated with the incidence of (pre)diabetes in people with normal glucose tolerance at baseline, independent of other risk factors. People with HSV2 were 59% more likely to develop (pre)diabetes than those who were HIV-negative, while CMV infection was associated with a 33% increase in the incidence of (pre)diabetes.

The study found that HSV2 and CMV contributed consistently and complementary to the development of (pre)diabetes, even after controlling for gender, age, BMI, education, smoking , physical activity, parental diabetes, hypertension, lipid levels, insulin resistance and fasting. glucose. HSV2 was also found to be associated with HbA1 C levels, independent of other confounding factors and the prevalence of (pre)diabetes itself.

The authors state: “Our study suggested that while the incidence of (pre)diabetes was primarily explained by age, BMI, cholesterol and fasting blood glucose, HSV2 and CMV added additional information about risks, despite high viral prevalence and co-occurrence.

The mechanisms by which these viruses could contribute to the development of (pre)diabetes remain to be discovered. 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 the metabolic syndrome.

The authors conclude: “These results highlight the link between viruses and (pre)diabetes, and the need for further research to assess viral prevention strategies in public health, possibly including the development of effective vaccines against them. herpesvirus.

Dr Annette Peters, Ludwig-Maximilians & Helmholtz University Munich, Germany. T) +49 89 3187 4566 E) peters@helmholtz-muenchen.de

Alternate Contact Tony Kirby from Tony Kirby PR. T) +44 7834 385827 E) tony@tonykirby.com


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