Diet, genetic susceptibility, latent autoimmune diabetes in adults, type 1 and type 2 diabetes

Abstract

Diabetes is one of the most common chronic diseases, yet our understanding of modifiable risk factors remains incomplete. This project aimed to elucidate the role of diet in the risk of latent autoimmune diabetes in adults (LADA), type 1 and type 2 diabetes and explore whether genetics modify this relationship.

Paper I was a systematic review and meta-analysis examining the evidence on the association between diet and the risk of type 1 diabetes. The most compelling evidence suggested that longer breastfeeding and later introduction of gluten may reduce the risk of type 1 diabetes, while higher cow’s milk intake in childhood may increase the risk. Other factors in infancy and childhood were also associated with type 1 diabetes, but the evidence was of low certainty.

Paper II, based on the European EPIC-InterAct case-cohort, found no associations between dairy products and the risk of islet autoimmunity or diabetes in adults. However, circulating fatty acids 15:0 and 17:0, proposed biomarkers of dairy fat, were associated with a reduced risk of diabetes in individuals with and without islet autoimmunity. Furthermore, low 17:0 concentrations were associated with a higher risk of progressing from marked autoimmunity to adult-onset diabetes.

In Paper III, data from the Swedish ESTRID case-control study was used to investigate the association between the intake of antioxidant nutrients and the risk of LADA and type 2 diabetes. These results were complemented with Mendelian randomization (MR) analyses. The findings indicated inverse associations between dietary vitamin C and E with LADA with more evidence of autoimmunity but not LADA with low autoantibody levels or type 2 diabetes. The results for vitamin E were further supported in MR analyses.

Paper IV utilized data from ESTRID and the Norwegian HUNT cohort. The results indicated inverse associations between moderate alcohol consumption and the risk of LADA and type 2 diabetes. Moreover, it was revealed that inverse associations with LADA were limited to those with high genetic susceptibility to type 2 diabetes. In contrast, inverse associations with type 2 diabetes were evident only in individuals with low genetic susceptibility to the disease.

This research emphasizes the potential of diet in preventing diabetes and proposes that the effects of different dietary factors may vary across the life course and are likely influenced by genetic susceptibility to diabetes.