The results, which suggest the bacteria may play a role in the development of diabetes in adults, are available online in The Journal of Infectious Diseases.
There have been several studies evaluating the effect of the presence of H. pylori on diabetes outcomes, but this is the first to examine the effect on HbA1c, an important, objective biomarker for long-term blood sugar levels, explained Yu Chen, PhD, MPH, associate professor of epidemiology at NYU School of Medicine, part of NYU Langone Medical Center.
"The prevalence of obesity and diabetes is growing at a rapid rate, so the more we know about what factors impact these conditions, the better chance we have for doing something about it," Dr. Chen said. Looking at the effects of H. pylori on HbA1c, and whether the association differs according to BMI status, provided what could be a key piece of information for future treatment of diabetes, she explained.
Type II diabetes causes an estimated 3.8 million adult deaths globally. There have been conflicting reports about the association between H. pyloriinfection and type II diabetes. To better understand the relationship betweenH. pylori and the disease, Dr. Chen and Martin J. Blaser, MD, the Frederick H. King Professor of Internal Medicine and professor of microbiology, analyzed data from participants in two National Health and Nutrition Surveys (NHANES III and NHANES 1999-2000) to assess the association between H. pylori and levels of HbA1c.
"Obesity is an established risk factor for diabetes and it is known that high BMI is associated with elevated HbA1c. Separately, the presence of H. pyloriis also associated with elevated HbA1c," said Dr. Blaser, who has studied the bacteria for more than 20 years. "We hypothesized that having both high BMI and the presence of H. pylori would have a synergistic effect, increasing HbA1c even more than the sum of the individual effect of either risk factor alone. We now know that this is true."
H. pylori lives in the mucous layer lining the stomach where it persists for decades. It is acquired usually before the age of 10, and is transmitted mainly in families. Dr. Blaser's previous studies have confirmed the bacterium's link to stomach cancer and elucidated genes associated with its virulence, particularly a gene called cagA.
Regarding H. pylori's association with elevated HbA1c, Drs. Chen and Blaser believe the bacterium may affect the levels of two stomach hormones that help regulate blood glucose, and they suggest that eradicating H. pylori using antibiotics in some older obese individuals could be beneficial.
More research will be needed to evaluate the health effects of H. pylori and its eradication among different age groups and in relation to obesity status, the authors noted.
"If future studies confirm our finding, it may be beneficial for individuals at risk for diabetes to be tested for the presence of H. pylori and, depending on the individual's risk factor profile" Dr. Chen.
In an accompanying editorial in The Journal of Infectious Diseases, Dani Cohen, PhD, of Tel Aviv University in Israel, pointed out that while previous studies have addressed the association between type II diabetes and H. pyloriin small samples, this study analyzed two independent large national samples of the general population. Dr. Cohen agreed with the study authors, suggesting that adults infected with H. pylori with higher BMI levels, even if asymptomatic, may need anti-H. pylori therapy to control or prevent type II diabetes. If the study findings are confirmed, Dr. Cohen wrote, they "could have important clinical and public health implications."