The aim of the study is to describe the inflammatory response to enzimatic glucose sensors after 10 days of use and to evaluate the relationship between the magnitude of the FBR (foreign body response) with the accuracy of the sensor (MARD)

Eighteen Type 1 DM patients are going to be included. Primary Objectives

1. To define the intra-individual and inter-individual variability of the macrophage count around the sensor
2. To assess whether there is a relationship between the number of macrophages, fibrosis and MARD of the MCG registry.

Secondary Objectives

To describe the histology of tissue response. This description will include:

1. HE stain: cell types, arrangement, vascular structures, signs of hemorrhage-clot. Giemsa stain: mast cells. Masson's trichrome stain: str. vascular.
2. Immunohistochemistry: Vascular assessment, characterization of macrophages

Each patient will have 1 glucose sensor inserted in the non-dominant arm. During the useful life of the sensor (10), a minimum of 4 capillary blood glucose determinations/day will be performed The sensor has a length of 8 mm and a diameter of 0.4 mm. All the necessary material will be provided, including a control diary to help the patient remember to carry out the self-control and set its time distribution.

On the last day of sensor use, it will be removed and a 4-mm punch skin biopsy will be performed 5 minutes later.

Tissue samples will be fixed in 4% formaldehyde solution, paraffin blocks made and sectioned. The resulting samples will be stained Semiquantitative determination of lymphocytes, neutrophils, mast cells, macrophages will be performed; fibrin, fibrosis, vascular proliferation and karyorrhexis

In all cases, a quantitative immunohistochemical study will be performed with x40 field counting with photographs and grid (Dako omnis with envision system) for:

Macrophages

The monitor-glucometer will be recovered for download and study of the record. The interstitial glucose - blood pairs will be made with those recorded but not used for callibration.

Glucose sensor values and insulin doses will be recover from tha medical application

Inclusion Criteria:

• 1. Type 1 diabetes of more than 6 months duration, confirmed by positivity for Ab antiGAD 65 2. Be a regular user of a continuous glucose monitoring system 2. To Understand the proposed protocol and acceptance of participation.

Exclusion Criteria:

• Treatment with drugs that could potentially modify the inflammatory response during the 10 days prior to surgery (non-steroidal anti-inflammatory drugs or corticosteroids, antioxidants or platelet antiaggregants).

Eighteen people diagnosed with type 1 diabetes and treated with closed-loop systems