Re: Association between maternal gluten intake and type 1 diabetes in offspring: national prospective cohort study in Denmark
Several limitations weaken the conclusions which should be drawn from the large prospective cohort study attempting to relate maternal gluten intake to incidence of type 2 diabetes in offspring reported in the BMJ (1).
First, the models presented do not consider potential confounding by other dietary factors. It is conceivable that other constituents of gluten containing foods may be involved. The two previous studies which have examined this question reported intake of either cereal products or gluten containing foods (2,3).
Second, the dose response assumes linearity and is set on a prohibitive 10-gram increase in gluten per day, not far from the average daily intake of 13-grams. A more realistic dose may not produce a significant association given the lower confidence interval in the paper was stated as 1.001. Confidence intervals for all analyses were wide including both a minimal effect and a strong adverse effect given the low number of events recorded. This imprecision warrants a cautionary interpretation. The quantile analysis undertaken to support the dose response analysis relied on extreme deciles that do not represent the intakes of 80% of people in this study.
Third, no information is provided regarding absolute risks which would have helped to determine the potential clinical significance of the findings.
While the research question is important and the report by Antvorskov and colleagues contributes to the available body of evidence we question the extent to which the findings as presented provide evidence to implicate maternal gluten intake as an important contributor to risk of type 1 diabetes in offspring.
References
1. Antvorskov JC, Halldorsson TI, Josefsen K, et al. Association between maternal gluten intake and type 1 diabetes in offspring: national prospective cohort study in Denmark. BMJ 2018; 362: k3547.
2. Virtanen S, Uusitalo L, Kenward M, et al. Maternal food consumption during pregnancy and risk of advanced β‐cell autoimmunity in the offspring. Pediatric diabetes 2011; 12(2): 95-9.
3. Lamb MM, Myers MA, Barriga K, Zimmet PZ, Rewers M, Norris JM. Maternal diet during pregnancy and islet autoimmunity in offspring. Pediatric Diabetes 2008; 9(2): 135-41.
Competing interests:
No competing interests
02 October 2018
Andrew N Reynolds
Postdoctoral Research Fellow
Professor Jim Mann
Department of Medicine, University of Otago
Department of Medicine, PO Box 56, Dunedin Otago 9016, NEW ZEALAND
Rapid Response:
Re: Association between maternal gluten intake and type 1 diabetes in offspring: national prospective cohort study in Denmark
Several limitations weaken the conclusions which should be drawn from the large prospective cohort study attempting to relate maternal gluten intake to incidence of type 2 diabetes in offspring reported in the BMJ (1).
First, the models presented do not consider potential confounding by other dietary factors. It is conceivable that other constituents of gluten containing foods may be involved. The two previous studies which have examined this question reported intake of either cereal products or gluten containing foods (2,3).
Second, the dose response assumes linearity and is set on a prohibitive 10-gram increase in gluten per day, not far from the average daily intake of 13-grams. A more realistic dose may not produce a significant association given the lower confidence interval in the paper was stated as 1.001. Confidence intervals for all analyses were wide including both a minimal effect and a strong adverse effect given the low number of events recorded. This imprecision warrants a cautionary interpretation. The quantile analysis undertaken to support the dose response analysis relied on extreme deciles that do not represent the intakes of 80% of people in this study.
Third, no information is provided regarding absolute risks which would have helped to determine the potential clinical significance of the findings.
While the research question is important and the report by Antvorskov and colleagues contributes to the available body of evidence we question the extent to which the findings as presented provide evidence to implicate maternal gluten intake as an important contributor to risk of type 1 diabetes in offspring.
References
1. Antvorskov JC, Halldorsson TI, Josefsen K, et al. Association between maternal gluten intake and type 1 diabetes in offspring: national prospective cohort study in Denmark. BMJ 2018; 362: k3547.
2. Virtanen S, Uusitalo L, Kenward M, et al. Maternal food consumption during pregnancy and risk of advanced β‐cell autoimmunity in the offspring. Pediatric diabetes 2011; 12(2): 95-9.
3. Lamb MM, Myers MA, Barriga K, Zimmet PZ, Rewers M, Norris JM. Maternal diet during pregnancy and islet autoimmunity in offspring. Pediatric Diabetes 2008; 9(2): 135-41.
Competing interests: No competing interests