At 36 weeks, your fasting blood glucose of 100–108 mg/dL is only mildly elevated and very common, even with excellent post-meal sugars (120–131) and a superb
HbA1c of 5.3%, because third-trimester placental hormones (especially HPL, cortisol, and progesterone) peak dramatically and create intense overnight insulin resistance, causing the
liver to release extra glucose between 3–8 a.m.; this “accelerated dawn phenomenon” is often the last and most stubborn value to control on metformin alone, despite perfect daytime numbers. Pregnancy targets are strict (fasting ≤95, sometimes ≤90), so many women at this stage need either a higher bedtime dose of metformin, a protein-fat bedtime snack, an after-dinner walk, or—most commonly—a small dose of bedtime long-acting basal insulin (e.g., 4–10 units) to counteract the hormonal surge; this is normal physiology, not a failure on your part, and control this tight usually resolves immediately after delivery. Talk to your doctor this week—they will very likely adjust your regimen to bring fasting comfortably into target before 37 weeks. You’re doing an outstanding job!