The goal of this study is to evaluate a CGM-CKM device during insulin suspension in patients with type 1 diabetes. 10 patients with T1D will be recruited for a pilot study. The patients will visit CTRU at Stanford Medical School. The CGM-CKM device will be applied to the upper arm area of patients and baseline ketone and glucose measurement will be performed for one hour prior to suspending or disconnecting the pump. Upon baseline measurement, the pump will be disconnected for 3 hours while the electrochemical signals are collected from the CGM-CKM device. During the 3 hours of pump disconnection, blood samples will be collected every 5 minutes from participants for analyzing their insulin and glucagon using conventional ELISA kits and glucose and ketone using standard meters.

This is a non-significant risk (NSR) device study not conducted under an IDE, in accordance with 21 CFR 812.2(b)

Inclusion Criteria:

• Clinical diagnosis of type 1 diabetes for at least 1 year without significant endogenous insulin production
• Currently using insulin pump
• Understanding and willingness to follow the protocol and sign informed consent.
• Willingness to sign a consent for release of medical information at the time of enrollment
• Ability to speak, read and write in the language of the investigators.

Exclusion Criteria:

• History of DKA or severe hypoglycemia within the past 6 months
• eGFR <45 mL/min/1.73 m2 or other significant renal impairment
• Pregnancy or breastfeeding
• Current use of non-insulin medications affecting ketone production, including SGLT2 inhibitors
• Active skin infections or conditions affecting sensor application sites
• Known skin allergies to tapes or adhesives
• Current use of any long-acting insulin analogs
• A known medical condition that in the judgment of the investigator might interfere with the completion of the protocol

Sensor measurements and blood plasma levels will be shared via journal/conference publications.

No masking will be used.