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

Inclusion criteria

• Individuals who are planning to undergo GI cancer surgery according to their physician's advice
• Diagnosed with diabetes mellitus
• Aged 18 or above
• Can communicate in Mandarin or Taiwanese
• Agree to participate and sign the informed consent form

Exclusion criteria

• People who are under active treatment for cancer other than GI cancer
• Have a cognitive impairment
• Do not know that they have GI cancer
• Have medical-grade adhesives-related allergy (e.g., redness, swelling, heat, pain, itching, blisters or rash)
• Diagnosed with thrombocytopenia or blood coagulation dysfunction