The Aim of this interventional study in to assess the effect of the use of a smartpen connected by an APP to continuous glucose sensors in a cohort of diabetic adolescents in not good metabolic control.

Primary endpoint: time in range Secondary endpoints: other glucometrics, Hba1c, treatment satisfaction.

Inclusion Criteria:

1. Age between 12 - 18 years
2. A clinical diagnosis of diabetes type 1 as determined by investigator for at least 12 months.
3. HbA1c >7.5% (DCA)
4. Subject is on multiple daily injection therapy (3 or more insulin injections per day one of which is a long acting insulin injection), is currently using or is willing to use insulin pens and pen cartridges and are not willing to use an insulin pump or AHCL system
5. Subject is currently using a CGM or is willing to use the Guardian 4 system during the study.
6. Subject and parents agree to comply with the study protocol requirements
7. Subject and parents provide their signature on the Informed Consent Form

Exclusion Criteria:

1. Subject is unwilling or unable to use insulin pen(s).
2. Subject is in plans to use or is already using an insulin pump.
3. Subject is currently using a non-Medtronic standalone CGM system and unwilling to use only the Guardian 4 system during the study.
4. Subject has any unresolved adverse skin condition in the area of device placement (e.g. psoriasis, rash, Staphylococcus infection).
5. Subject is actively participating in or plans to enroll in an investigational study (e.g. drug or device), other than this study, wherein they have received treatment from an investigational drug or device.
6. Subject has a positive urine pregnancy test at time of screening.
7. Subject is unwilling to participate in study procedures.
8. Subject is directly involved in the study as research staff.
9. Subject with poorly controlled thyroid or celiac disease.
10. Subject with any risk of exposure to MRI equipment, diathermy devices or other devices capable of generating strong magnetic fields