Results were not accurate; despite multiple efforts to troubleshoot.

The overall goal for this pilot clinical trial is to explore the accuracy and acceptability of a non-invasive, wearable glucose sensor in patients living with DM. This study will compare needleless glucose sensor readings with glucometer measurements from patients with type 1 or type 2 diabetes (T1DM or T2DM), under varying conditions.

Self-monitoring of blood glucose (SMBG) can both facilitate and hinder adherence in patients with diabetes mellitus (DM). Readings provide real-time information on hypoglycemic and hyperglycemic excursions. These data are crucial to successfully managing this disease, as SMBG can help guide decisions on titrating medications, and can potentially encourage patient engagement. There are drawbacks. Piercing the skin to check glucose up to several times a day can be uncomfortable and obtrusive for a patient with DM. SMBG offers only a snapshot of the patient's glucose at the time of testing.

Continuous glucose monitoring (CGM) can reveal glucose trends. A subcutaneous sensor transmits interstitial glucose readings approximately every five minutes. Yet, sensor insertion requires a needle. Patients still must test SMBG about 4 times per day to calibrate the CGM sensor. This modality is less accurate with low or rapidly rising glucose. CGM is also not widely available, due to cost and insurance issues. A non-invasive glucose monitor, the GlucoWatch, was discontinued due to problems with accuracy and tolerability.

Compounding these challenges is the surging number of individuals with DM. Every 19 seconds, an American 20 years of age or older is diagnosed with DM. If current trends continue, 1 in 3 Americans could have DM by 2050.

There is thus an unmet need for a non-invasive glucose monitoring device. UCSD nanoengineers developed a flexible, ultra-thin sensor adherent to the skin, similar to a temporary tattoo. Preliminary data from seven individuals without DM demonstrated correlation between glucose measurements from this sensor and a glucometer. Evaluating this sensor in patients with DM will be critical: while hour-to-hour blood glucose fluctuates approximately 50% throughout the day in those without DM, it may vary up to 10-fold in patients with DM. This study would be the first to examine this sensor in individuals with DM. The investigators hypothesize that compared with a glucometer, a tattoo sensor can accurately measure glucose in patients with DM.

Inclusion Criteria:

1. An existing diagnosis of diabetes mellitus, either T1DM or T2DM
2. Absence of cognitive impairment, as demonstrated by a Montreal Cognitive Assessment (MOCA) score greater than 26; those individuals with questionable cognitive ability will be screened with this instrument.
3. Ability to provide informed consent for participation.

Exclusion Criteria:

1. Individuals without diabetes
2. Those who have a MOCA score of 26 or less
3. Those who cannot speak or read English. The investigators are limiting participation to those who read and speak English, as this is a pilot study of a small number of participants, that will very unlikely offer the prospect of direct benefit from participating.
4. Individuals who have a cardiac, respiratory, or other condition that would preclude safely exercising at a moderate pace. Along with a medical history and physical examination by the PI, prospective participants will complete the Physical Activity Readiness Questionnaire (PAR-Q) to help determine those who may safely exercise for this study. One or more "yes" responses does not necessarily exclude an individual from participating.
5. Individuals who have frequent hypoglycemia, hypoglycemia unawareness, or who are at high risk for hypoglycemia.