You may want to look at what type of food she has eaten which could be the cause of varying readings. The carbs in some types of food take longer to digest and turn into glucose, other types of food contain carbs that turn into glucose much more quickly. For example, pasta or carbohydrate foods containing a high fat content (like pizza) can result in a slower rise in blood sugars than foods containing a quicker acting carbohydrate like potatoes or white bread. This might explain the difference in readings at 2 hours after the meal. If she's had a fruit juice or some other form of quick acting carbohydrate then her readings will be higher 2 hours after the meal than if she's not had this quick acting carbohydrate.
Another thing that affects post meal readings is the amount of exercise done after injecting. If your daughter has been more active shortly after the injection it can cause the insulin to be absorbed more quickly resulting in lower readings at 2 hours than expected. In the early days of my daughter having diabetes we learned this the hard way. She had her meal and injection and then we rushed off to a country dancing event. Her readings dropped so quickly, I remember feeding her glucose sweets between dances trying to keep an acceptable level. It didn't help too that the meal had been pasta which at the time I didn't realise would result in a lower blood glucose at the 2 hour mark. It was a stressful evening that I never want to repeat.
As always it's best to chat with your diabetic nurse or care team before making any changes to insulin doses. It's always useful to have a record of readings and what has been eaten for the various meals in order for them to assess if her carb:insulin needs to be changed.
