An infusion device configured to implant a cannula and a sensor in a user. The infusion device includes a first unit defining a first housing and a second unit defining a second housing. The second housing is configured to engage the first housing. The infusion device includes a first insertion needle configured to implant the cannula in the user and a second insertion needle configured to implant the sensor in the user when the second unit engages the first unit. The infusion device includes processing circuitry in electrical communication with the sensor and a fluid reservoir in fluid communication with the cannula. In examples, the first unit and the second unit are configured to engage using an inserter.