This is a prospective, multi-center, non-randomized, single-arm, post-approval study of the FreeStyle Libre Flash Glucose Monitoring System intended to characterize the safety of the Libre Flash Glucose Monitoring System when used in people with diabetes.

Up to 920 adult subjects, aged 18 years and older with type 1 or type 2 diabetes, who require daily blood glucose monitoring to manage their diabetes, will be enrolled to obtain at least 736 subjects who complete the final visit. Subjects will utilize capillary SMBG for managing diabetes for 6 months (control phase) followed by diabetes management using FreeStyle Libre for 6 months (intervention phase). Subjects will maintain a diary/log book of Adverse Events during each phase. Assessment of Adverse Events will occur via self reporting at each monthly visit and/or phone call.

Inclusion Criteria:

• Subject must be at least 18 years of age.
• Subject must have a diagnosis of type 1 or type 2 diabetes mellitus.
• Subject is currently using SMBG for managing their diabetes.
• Subject must be able to read and understand English
• In the investigator's opinion, the subject must be able to follow the instructions provided to him/her by the study site and perform all study tasks as specified by the protocol.
• Subject must have access to an internet connected computer for uploading data from the blood glucose meter and FreeStyle Libre system.
• Subject must be willing and able to provide written signed and dated informed consent.

Exclusion Criteria:

• Subject is a member of the Site Staff.
• Subject is currently using or has previously used a continuous glucose monitoring system for managing their diabetes
• Subject has known allergy to medical grade adhesive or isopropyl alcohol used to disinfect skin.
• Subject is pregnant or is attempting to become pregnant at the time of enrollment.
• Subject is on dialysis at the time of enrollment.
• Subject has concomitant medical condition which, in the opinion of the investigator, could interfere with the study or present a risk to the safety or welfare of the subject or study staff.
• Subject currently is participating in another clinical trial.
• Subject is unsuitable for participation due to any other cause as determined by the Investigator.

Adult subjects aged 18 years and older with type 1 or type 2 diabetes, who require daily blood glucose monitoring to manage their diabetes. At least 20% of the study population will be age 30 or below and 15% will be age 65 or older.