Rudy Bilous, MD, FRCP
Richard Donnelly, MD, PHD, FRCP, FRACP
The vast majority of cases of diabetes in children are type 1, caused by autoimmune destruction of beta cells in the pancreatic islets. A steady increase in the incidence of type 1 diabetes has been reported worldwide (average increase 2.5-3% per year worldwide with significant geographical variations), especially in children aged less than 4 years. This suggests changes in environmental factors that operate early in life. The incidence of type 1 diabetes varies considerably between countries; for example, the lowest incidence is in China and the highest in Finland and Sardinia (Figure 28.1). Rarer causes of diabetes in childhood include cystic fibrosis (which usually requires insulin), the rare transient and permanent neonatal forms of diabetes, maturity-onset diabetes of the young (MODY, see Chapter 8) and various other genetic syndromes such as Down’s syndrome, Wolfram or DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness) syndrome, lipoatrophic diabetes and diabetes associated with mitochondrial mutations (see Chapter 8). Type 2 diabetes is also increasing in childhood….
Among children aged less than 14 years of age, the number of new cases of type 1 diabete in Europe in 2005 is estimated at 15,000. The predicted number of new cases in 2020 is more than 24,000 with a doubling in numbers diagnosed among children below five years. The prevalence of type 1 diabetes in Europe among those under 15 years is predicted to increase from 94,000 in 2005 to 160,000 in 2020 (Figure 28.2).
There is considerable geographical variation in the incidence of type 1 diabetes within Europe (up to 10-fold), but the explanation for these differences and the increasing trend towards younger age at diagnosis is unclear (Figure 28.3). The maternal and infant environment, as well as dietary factors, may be important. Data are inconsistent with respect to breastfeeding, and the introduction of cow’s milk and cereals. An emerging dietary risk factor may be the early consumption of root vegetables (potatoes, carrots, etc.) between 3-4 months of age, and it is interesting that per-capita consumption of potatoes correlates with the incidence of type 1 diabetes in different countries. Other possible triggers for type 1 diabetes in early life include placental transmission of enteroviruses, food toxins and cereals which could activate autoimmune pathways during pregnancy.