The purpose of this study is to compare glucose measurements from the C8 MediSensors non-invasive Optical Glucose Monitor™ System to blood glucose measurements from the Yellow Springs Instrument(YSI) blood glucose analyzer.

This is a prospective, non-randomized, open label study to evaluate the performance of the C8 MediSensors non-invasive Optical Glucose Monitor™ on individuals with diabetes mellitus. Capillary blood samples will be obtained throughout a daily study session; the study session may last for up to 12 hours. Blood glucose will be measured on a YSI blood glucose analyzer. Subjects may adjust food intake and insulin administration so device performance is evaluated across a broad range of glucose concentrations. Glucose measurements will be time matched and paired for comparison. Skin effects and adverse events will be evaluated.

Inclusion Criteria:

1. 18 years of age or older.
2. Understands and agrees to comply with study instructions.
3. Read, understood, signed and dated the Informed Consent Form.

Exclusion Criteria:

1. Pregnancy.
2. Extensive skin changes or diseases that preclude wearing the test device at the proposed wear site(s) (e.g., extensive psoriasis, recent burns or severe sunburn, extensive eczema, extensive scarring, extensive tattoos, dermatitis herpetiformis).
3. Employed by a company within the diabetes field other than the study sponsor.
4. Medical history or any condition that may, in the opinion of the investigator, compromise the subject's ability to participate.