The Impact of Coexisting Coeliac Disease on Type 1 Diabetes

Abstract

Coeliac disease (CD) coexists with type 1 diabetes (T1D) substantially more than in the general population. This body of work examines the broad and pervasive relationship between CD on T1D, including the epidemiology, screening practices, microvascular complications, quality of life (QoL), nutrition, glycaemic variability, and bone health. In particular, the contribution of gluten free diet (GFD) adherence is explored. Study 1: The 20-year incidence of CD in 4,379 people with T1D aged <18 years was 7.7 per 1000 person years. Incidence was significantly higher in those with T1D onset < age 5 years, but this subgroup developed CD after significantly longer T1D duration than those with T1D onset >5 years. Study 2: We systematically reviewed the epidemiology of CD in 11,157 youth with T1D alone and 587 with coexisting CD; 55% of CD cases were diagnosed within 2 years of T1D and 79% within 5 years. We concluded that CD screening should be performed at T1D diagnosis and repeated within 5 years of T1D. Study 3: Comparing 129 youth with T1D and CD vs 2,510 with T1D alone, retinopathy, albumin excretion rate (AER) and neuropathy did not differ. HbA1c was lower in those with CD (8.3% vs 8.6%, p=0.04), however elevated AER was more prevalent in those who did not adhere to the GFD (40% vs 23%, p=0.04). Study 4: In a case control study of 35 youth with T1D and 35 with coexisting CD, and their carers, generic and diabetes-specific QoL did not differ. Youth using insulin pumps had similar generic and diabetes specific QoL to those using multiple daily injections. However, those who did not adhere to the GFD had lower diabetes specific QoL and lower general wellbeing, as did their carers. Study 5: In a case control study using continuous glucose monitoring, youth with T1D and CD had greater glycaemic variability, with a shorter time to peak blood glucose levels (BGL), higher peak, and higher postprandial BGLs than T1D alone, despite similar pre-meal BGLs. Both groups had inadequate calcium, folate and fibre, with excessive saturated fat and sodium intake. Study 6: In a case control study utilising dual energy x-ray absorptiometry and peripheral quantitative computational tomography, youth with coexisting T1D and CD had lower bone mineral content, abnormal trabecular and cortical bone development, and a lower bone turnover state with reduced muscle pull vs T1D alone. These studies further our understanding of the impact of coexisting CD in T1D. The findings inform screening and management of CD, and provide evidence in support of GFD adherence to optimise clinical, dietary, and psychosocial management.