Hi,
The high reading is likely due to a combination of what you ate(carbohydrate load, sweet drinks etc) as well as your medication not quite covering it.
You can
cutCuts and puncture wounds back on your carb load to see what happens. But you can also have your medications adjusted or changed entirely to prevent that big rise. The change ofcourse will depend on what you are currently taking.
Non-medication suggestions: Drinking water does help, so in the meantime you should also do that. For some, going for a walk also helps bring their sugar down.
Take care.