The main goal is to investigate whether beta cell mass is correlated to beta cell function after autologous faecal microbial transplantation (FMT) in patients with newly diagnosed type 1 diabetes

The incidence of Type 1 Diabetes Mellitus (T1D) has tripled in the last thirty years, and T1D is associated with a lifelong increase of considerable morbidity and mortality compared to healthy subjects. As the increased T1D incidence is primarily observed in subjects who are not genetically predisposed, environmental factors including altered diet, antibiotic use as well as mode of birth have been suggested to play a role, and these factors have invariably been linked to changes in the gut microbiome. Indeed, an altered composition of the faecal microbiota composition was observed in adolescent T1D patients. A previous study by de Groot et al. (2021) showed that faecal microbiota transplantation stops the decline in endogenous insulin production in newly diagnosed type 1 diabetes patients. However, it is unknown whether this is due to an increase in beta cell mass, or increased function of the remaining beta cells.

In this study, the investigators aim to investigate whether beta cell mass (quantified by 68Ga-NODAGA-exendin-4 PET/CT imaging) is correlated to beta cell function after autologous faecal microbial transplantation in patients with newly diagnosed type 1 diabetes.

Inclusion Criteria:

• Previously participated in ENCAPSULATE-DM1 or FMT preserve-DM1 trial
• Type 1 diabetes with the diagnosis being made in the last 4.5 years
• Presence of at least one autoantibody associated with type 1 diabetes (anti-GAD-65, anti-IA2, islet cell antibodies, insulin autoantibodies)
• Age ≥ 18 years
• BMI 18-30 kg/m2
• Insulin use

Exclusion Criteria:

• Inability to provide written informed consent
• Other medication use than insulin
• Smoking
• Evidence of compromised immunity
• Presence of a second autoimmune disease (other than type 1 diabetes); e.g. celiac disease, hyper- or hypothyroidism, inflammatory bowel disease. Vitiligo is allowed.
• Pregnancy or the wish to become pregnant within 1 month after the study
• Breastfeeding
• Liver disease defined as aspartate aminotransferase or alanine aminotransferase level of more than three times the upper limit of normal range
• Renal disease defined as MDRD < 40 ml/min/1.73 m²