Impact of Glycemic Variability on People With Gastrointestinal Cancer and Diabetes After Surgery

In study phase 1, the investigators will prospectively examine the factors related to post-operative glycemic variability and its effect on outcomes in people with both DM and GI cancer after surgery. The study will also qualitatively understand the glycemic variability experiences and their associated symptoms and outcomes in people with both DM and GI cancer. In study phase 2, the investigators will develop and test the effects of the CGM-Assisted Reflection Education (CARE) program on adults with both DM and GI cancer post-surgery.

Diabetes mellitus (DM) often coexists with gastrointestinal (GI) cancer, and poor post-operative glycemic control is hypothesized as a major cause of patients' worse health-related outcomes. No study to date has developed and tested a program that focuses on improving DM self-care through glycemic variability reflection using continuous glucose monitoring (CGM) in people with both GI cancer and DM after surgery. This study aims to (1) prospectively examine the relationships among factors influencing glycemic variability and outcomes (DM self-care, HbA1c, DM distress, fatigue, and quality of life) in adults with DM and GI cancer during the first year post-surgery; (2) qualitatively explore the glycemic variability experiences; and (3) develop and test the effects of the CGM-Assisted Reflection Education (CARE) program on DM self-care and the secondary outcomes. This study consists of two phases. Phase one will utilize a longitudinal mixed-methods design with 200 participants recruited from GI surgical outpatient departments, collecting data via structured questionnaires at four time points: before surgery, 3, 6, and 12 months post-surgery. Data will be analyzed using SPSS version 28 and Mplus version 8.6 under a structural equation modeling approach. A subsample of 21 participants will undergo semi-structured interviews for qualitative insights. In study phase two, the CARE program will be developed and tested using a randomized controlled trial design. A total sample of 60 participants (30 in each group) will be recruited and randomly assigned in a 1:1 ratio to the experimental and the control group. The experimental group will receive usual care plus the CARE program. The control group will receive usual care. Outcomes will be measured using the same set of questionnaires from phase one, and the data will be collected pre-intervention, 8 weeks, 3-, and 6 months after intervention.