Off Pod for 4 hrs

Our daughter (10yrs old) was diagnosed with T1 than 18 months ago. We thought she had come out of honeymoon when her insulin needs almost doubled after 6 months of diagnosis and since then it has not changed. But for the couple of days strange things are happening. After 1 hr of lunch she goes low ( 50 to 70) which only gets treated when we give around 100 grams worth of sugar and her pump is switched off for 4 hrs. This has never happened before.Then she eventually goes up and we hook her back on pump. Has anyone experienced this? We spoke to the nurse and she asked us to decrease her lunch bolus but my point is when she does not even require a basal, how would this help?