**7. Diabetes mellitus type 1 (DMT1) and associated CD**

In children, the first cases with CD and associated DMT1 were reported in 1969 [41]. Thus, a 10-year controlled longitudinal monitoring study of 335 adult celiac patients, diagnosed between 1980 and 1990, compared with a broad group of age- and sex-matched control subjects with various gastrointestinal symptoms, confirmed the high prevalence of endocrine diseases in patients with CD (11.9% in patients versus 4.3% in the control group; p < 0.003). More recently, other researchers found a higher prevalence of type 1 diabetes mellitus (5.4–7.4%) in patients with CD compared with controls [42, 43].

DMT1 is diagnosed in more than 90% of cases before CD is confirmed. Patients with diabetes mellitus and symptoms associated with CD who are following a GFD show a clear overall clinical improvement. In children, an increase in the growth rate and a rise in haemoglobin levels are often observed. Better metabolic control of diabetes mellitus is observed, as clearly confirmed by the reduction in the number of hypoglycaemic episodes, and the reduced need for daily insulin if the patient is following a GFD [44].

Juvenile diabetic patients present an average prevalence of CD of about 5% of cases. This strong association is largely due to the fact that celiac patients with and without diabetes share the same genetic base represented by the presence of the HLA-II haplotype, DR3-DQ2, demonstrating that it is appropriate to systematically screen for CD in patients with T1DM. Strategies for follow-up include periodic serological determinations for specific antibodies, first at the time of diagnosis, then, repeated every 6 months for the first year and at least annually for 5 years or more. Patients with positive responses to specific serological tests and in whom genetic susceptibility markers (HLA-DQ2 and/or HLA-DQ8) are present require duodenal biopsies to be taken to confirm the diagnosis of CD. Although many clinical

guidelines recommend carrying out systematic screening for CD, their application in clinical practice, particularly in children, adolescents and young adults, has not yet reached the desired level of performance in many countries of the world [45, 46].
