The investigators will measure blood levels of 1,5-anhydroglucitol in children with type 1 diabetes and correlate them with parameters related to functional beta-cell mass in diabetic patients. The values will be compared to those obtained in healthy volunteers. Children with newly diagnosed diabetes as well as children with longstanding disease will be included. The aim of the study is to test the validity of 1,5-anhydroglucitol as a novel biomarker of beta-cell mass and function in type 1 diabetes.

One-center prospective exploratory pilot study performed in collaboration between the Pediatric Endocrine and Diabetology unit of the University Hospitals of Geneva (HUG) and Prof. Pierre Maechler, Diabetes Center of the Faculty of Medicine, University of Geneva Switzerland.

1,5-anhydroglucitol (1,5-AG), a deoxyhexose present in almost all foods and forming a stable pool in human subjects, has recently been found to be correlated with functional beta-cell mass in two different mouse models of beta-cell dysfunction leading to diabetes. The decline of this biomarker precedes the development of hyperglycemia in lean b-Phb2 -/- and obese db/db diabetic mice, where beta-cell loss occurs through two different mechanisms.

Additional studies have shown a correlation of 1,5-AG levels with risk of progression of type 1 diabetes (T1DM) in auto-antibody positive children, as well as with glycaemic control in patients with type 2 diabetes.

The present project will analyse the correlation between functional beta-cell mass and the circulating levels of 1,5-AG in children with T1DM. This should contribute to the evaluation of a novel biomarker of beta-cell mass and function in T1DM.

Inclusion Criteria:

• Type 1 diabetes with positive autoantibodies against islets, insulin, islet antigen 2 (IA2), glutamic acid decarboxylase (GAD) 65 or zinc transporter (ZnT)8.
• Treatment with continuous subcutaneous insulin infusion (CSII) with or without automated insulin delivery (AID).
• Monitoring with a continuous glucose measurement system (CGMS) or flash glucose monitor (FGM).
• Patient willing to keep the same type of CGMS or FGM during the year of observation
• Ability to give informed consent as documented by signature

Exclusion Criteria:

• Patients treated with multiple daily injections (MDI) or not willing to wear a CGMS of FGM
• Patients changing the type of CGMS during the course of the study.

Among children with type 1 diabetes, aged 2 to 18 years:

15 newly diagnosed patients and 15 age- and sex-matched controls. 5 patients with a diabetes duration of 3 (36 - 47 months), 5 patients with a disease duration of 5 (60 - 71 months) and 5 patients with a disease duration of 10 years (120 - 131 months) and 15 corresponding age- and sex-matched controls.