Assessment of Mealtime Bolus Insulin Behavior

Inclusion Criteria: * Have a Type 1 Diabetes Mellitus (T1D) or a Type 2 Diabetes Mellitus (T2D) diagnosis * Must be taking a mealtime bolus dose insulin, greater than or equal to (≥) 3 doses * Each individual bolus insulin dose must be less than (\<) 40 units * Must be taking a stable insulin dose regimen for the last 3 months * Must be taking a bolus insulin analog (for example insulin lispro \[U-100\]/\[U-200\], insulin aspart, or insulin glulisine). In addition, must be able to switch to insulin lispro U-100 for the duration of the trial * Must have a hemoglobin A1c (HbA1c) ≥8.0% in the last 6 months * Participants with T1D must be ≥21 to less than or equal to (≤) 65 years of age. Participants with T2D must be ≥35 to ≤65 years of age * Women of childbearing potential must meet the following: (Note: females of childbearing potential are defined as those who have experienced menarche and who are NOT permanently sterile or postmenopausal. Postmenopausal is defined as 12 consecutive months with no menses without an alternative medical cause) * Must agree to use 1 highly effective method of contraception, or a combination of 2 effective methods of contraception for the entirety of the study * Must test negative for pregnancy as indicated by a negative serum or urine pregnancy test * Participants with prior CGM/flash glucose monitoring experience must have stopped CGM/flash glucose monitoring ≥3 months prior to enrollment Exclusion Criteria: * Have known tape/adhesive allergies with CGM sensors * Medical conditions, visual, physical, psychiatric, or cognitive impairment(s) that may preclude the ability to participate in the trial * Have history of liver disease, acute or chronic hepatitis, or alanine aminotransferase or aspartate aminotransferase levels ≥3 times the upper limit of the reference range within the last 6 months * Have history of chronic kidney disease stage 4 and higher within the last 6 months, or history of renal transplantation * Have active malignancy * Are pregnant or planning to become pregnant * Are on or are intending to begin a weight loss program * Participants with T1D who have taken off-label antihyperglycemic agents within last 3 months * Have received insulin by continuous subcutaneous insulin infusion in the last 3 months * Participants taking opioid medications for medically invalid reasons or at doses considered excessive * Participants on routine use of acetaminophen * Currently undergoing systemic treatment with: * Immunosuppressive medication * Chronic (lasting longer than 2 weeks) systemic glucocorticoid therapy (excluding topical and inhaled preparations) or have received such therapy within the prior 2 weeks * Are currently enrolled in any other clinical study involving an investigational product or any other type of medical research judged not to be scientifically or medically compatible with this study * Have participated, within the last 30 days, in a clinical study involving an investigational product * Are unwilling or unable to comply with the use of a data collection device to directly record data