Glucose Monitoring in PIK3CA-Mutated HR+/HER2-Negative Advanced Breast Cancer

Dr. Jason Mouabbi reviews the treatment initiation and early glucose monitoring strategy for a patient with PIK3CA-mutated HR-positive/HER2-negative advanced breast cancer receiving inavolisib in combination with palbociclib and fulvestrant. The patient receives baseline fasting glucose and HbA1c assessment, counseling regarding hyperglycemia, and home glucose monitoring. By day 7, her fasting glucose has increased to 148 mg/dL without symptoms, prompting more frequent monitoring and reinforcement of dietary and lifestyle counseling. Dr. Mouabbi explains that hyperglycemia can develop early during treatment and emphasizes close monitoring during the first week. He describes checking fasting blood glucose three times during the first week, followed by weekly monitoring during the next 3 weeks, every 2 weeks for the subsequent 8 weeks, and then monthly monitoring if glucose remains stable. He also discusses continuing HbA1c assessment every 3 months during treatment. The discussion emphasizes more intensive monitoring early in therapy, with decreasing frequency over time when glucose levels remain controlled.