Patients with celiac disease have a significantly lower prevalence of type 2 diabetes than do matched controls without celiac disease and the general population, Dr. Toufic A. Kabbani and his colleagues reported in a study published in the May issue of Gastroenterology.
Moreover, "the possible explanation that the lower rate of NIDDM [non–insulin-dependent diabetes mellitus] in individuals with celiac disease is due to different body mass index distribution is not supported by our study data, as the lower prevalence of NIDDM in celiac disease remains significant after controlling for BMI," they added.
Source: American Gastroenterological Association
Dr. Kabbani, of the Celiac Center at the Beth Israel Deaconess Medical Center, Boston, looked at the records of 840 adults with biopsy-proven celiac disease to determine the prevalence of type 2 diabetes or metabolic syndrome. The data were culled from the Celiac Center’s database.
Patients were matched by age, sex, and ethnicity to 840 controls without celiac disease chosen at random from a list of adults presenting to their primary medical provider for an annual checkup.
Patients were also compared with a cohort from the National Health and Nutrition Examination Survey (NHANES) population for reference.
According to the authors, both the celiac disease cohort and their matched counterparts were mainly white (88.9%) and female (72.5%).
Overall, 26 patients in the celiac group had type 2 diabetes (3.1%), compared with 81 controls (9.6%, P less than .0001) (Gastroenterology 2013 Jan. 28 [doi: 10.1053/j.gastro.2013.01.033]).
The prevalence of type 2 diabetes among celiac patients was also significantly lower than the estimated national prevalence derived from NHANES, which was 9.8% (P less than .0001).
Similarly, celiac patients recorded a significantly lower prevalence of metabolic syndrome than did controls (3.5% vs. 12.7%, P less than 0.0001).
Next, the authors conducted a multivariate analysis in which they controlled for BMI and smoking among celiac disease patients. The significantly negative association between celiac disease and type 2 diabetes persisted, with an odds ratio for diabetes among celiac patients of 0.49 (95% confidence interval, 0.29-0.83; P = .008).
"The mechanisms by which individuals with celiac disease are protected from NIDDM and metabolic syndrome are not clear at this time; however, possible explanations include altered pancreatic function, impaired nutrient absorption, and changes in gastrointestinal endocrine function," postulated the authors.
Alternatively, they wrote: "Tissue transglutaminase (tTG) drives inflammation in celiac disease via the down-regulation of peroxisome proliferator–activated receptor gamma (PPARG). On the other hand, PPARG up-regulation has been implicated in [type 2 diabetes] susceptibility.
"Therefore, the down-regulation of PPARG in celiac disease may be implicated in decreased risk of [type 2 diabetes]," the authors said.
Dr. Kabbani conceded that this study had several limitations. For one, most patients did not have an available waist circumference measurement, which is a criterion for metabolic syndrome, according to the International Diabetes Federation. As a proxy, the authors used a BMI of greater than 30 kg/m2. "While this might have affected the prevalence of metabolic syndrome in our study, we expect its impact on our analysis to be minor," they wrote.
Additionally, most celiac patients who started a gluten-free diet did not have endoscopic follow-up to assess intestinal healing.
However, "91.2% of these subjects had clinical improvement as well as normalization of their tTG titers, which increases the likelihood of histological improvement or remission."
None of the authors disclosed any financial conflicts relevant to this study. They disclosed no outside funding.