# Case Report: Usefulness, effectiveness, and safety of an advanced hybrid closed-loop system in a child with early identification of type 1 diabetes

## TL;DR

A hybrid closed-loop system helped manage early-stage type 1 diabetes in a child, maintaining good glucose control without severe issues.

## Contribution

Demonstrates the effectiveness of AHCLs in early-stage T1D with low insulin needs and good metabolic control.

## Key findings

- The Tandem t:slim Control-IQ® system maintained TIR > 80% without severe hypoglycemia or DKA.
- Low insulin requirement (0.1 U/kg/day) was sufficient for metabolic control in early-stage T1D.
- A two-step approach using CGM followed by AHCLs improved glucose management in early T1D.

## Abstract

The usefulness, effectiveness, and safety of advanced hybrid closed-loop systems (AHCLs) in early-stage 3 type 1 diabetes (T1D) are unknown. We report 9 months of continuous glucose monitoring (CGM) outcomes in a patient with early-stage 3 T1D treated with the Tandem t:slim Control-IQ® system. A 13-year-old girl, affected by celiac disease and Hashimoto’s thyroiditis, was diagnosed with T1D without symptoms (fasting c-peptide: 1.77 ng/ml; HbA1c: 6.4%) following an outpatient T1D screening program. She wore a CGM at diagnosis to closely monitor her glucose profile. After 6 months, when the time in range (TIR) fell below 80%, the Tandem t:slim Control-IQ® was initiated. Standardized CGM metrics, as well as instances of severe hypoglycemia and diabetic ketoacidosis (DKA), were recorded. CGM data guided the initiation of early insulin therapy. Tandem t:slim Control-IQ® system proved effective from the onset of T1D, with a low insulin requirement (0.1 U/kg/day, < 10 units/day) and maintained good metabolic control (TIR > 80%) without severe hypoglycemia or DKA. Based on our experience, we suggest a two-step approach for monitoring and treating patients with early stage 3 type 1 diabetes: first, positioning CGM, and second, when TIR falls below 80%, considering the addition of an AHCLs, even if the patient has a low insulin requirement.