Table 2. Summary of mentioned articles about clinical implications of T1DM and CD and impact on the quality of life.

T1DM, type 1 diabetes mellitus; CD, celiac disease; BPCD, biopsy-proven celiac disease; anti-tTG, anti-tissue transglutaminase antibodies; US, United States; HbA1c, hemoglobin A1c; GFD, gluten-free diet

Author	Year	Design	Population	Global Sample	Results	Conclusions
Abid et al. [35]	2011	Longitudinal study	T1DM children in the Royal Belfast Hospital for Sick Children in United Kingdom	468 children with T1DM	Mean age at T1DM diagnosis was 6.8 years and CD diagnosis 11.1 years. The majority (10 out of 11) had improvement in their gastrointestinal symptoms and six out of eight did not present more high-risk hypoglycemic episodes. However, the daily insulin requirement went up, from 0.88 to 1.1 unit/kg/day	A GFD improved the gastrointestinal symptoms and decreased episodes of severe hypoglycemia but the insulin requirement increased
Craig et al. [38]	2017		Youth with T1DM in three continents: US, Australia, and Europe (more specifically United Kingdom, Germany, and Austria)	52,721 individuals <18 years of age	BPCD was evidenced in 1,835 individuals, which represent 3.5% and the median age at diagnosis was 8.1 years (5.3-11.2 years). CD was diagnosed less than a year after T1DM diagnosis in 35%, between one and two years in 18%, between three and five years in 23%, and more than five years in 17%. The prevalence of CD went from 1.9% in US data to 7.7% in Australia and was higher in females than males (4.3% vs 2.7%).	T1DM individuals with coexisting CD were younger at the diagnosis than the ones with T1DM alone. HbA1c did not show any significant difference but height standard deviation score was lower in those with concomitant CD; therefore, a follow-up is recommended.
Rohrer et al. [39]	2015		Patients with T1DM from the German-Austrian DPV Database	56,514 individuals with T1DM less than 20-year duration	Nephropathy analyzed as microalbuminuria presented almost 10 years earlier in patients with CD versus non-CD: 32.8 years (29.7-42.5) vs. 42.4 years (41.4-43.3), and retinopathy in 25% of patients presented at 26.7 years (23.7-30.2) in CD patients versus 33.7 in non-CD patients	The presence of CD in a T1DM patient represents an independent risk factor for nephropathy and retinopathy, so in consequence the study recommends serologic tests of CD even in asymptomatic T1DM patients
Tittel et al. [40]	2021		Children and young adults from the German-Austrian DPV Database	79,067 children, adolescents, and young adults	In T1DM + depression, HbA1c was higher (9.0% [8.9-9.0]). in CD + T1D + depression (8.9% [8.6-9.2]), compared with T1D only (8.2% [8.2-8.2]). Also, anxiety, schizophrenia, and eating disorders are more frequently found in the T1D + CD + depression group compared with T1D group (p < 0.001).	Depression is significantly more frequent in T1DM with concomitant CD patients, also along with a higher HbA1c and anxiety and eating disorders compared to the T1DM group only. Thus, a screening for depression is recommended as routine as well to improve results and quality of life in those patients
Bhadada et al. [41]	2017	Retrospective study	Patients under 20 years old from Chandigarh, India	109 patients with T1DM under 20 years old	The age at diagnosis of CD and the time frame between the diagnosis of T1DM and CD were 11.5 ± 4.6 versus 13.8 ± 3.4 years and 48.8 ± 43.3 versus 20.2 ± 31.8 months in groups of CD alone and CD plus T1DM, respectively. Short stature (87% vs. 40.9%), anemia (80.9% vs. 45%), and delayed puberty (61.9% vs. 29.4%) were more frequent in CD alone group.	Patients with CD alone had a more delayed diagnosis than the ones with concurrent CD and T1DM and consequently to its late diagnosis, it led to more incidence of anemia, short stature, and delayed puberty