sugar spikes after meals

hi again im full of questions today..
i give my daughter novomix 30/70 and she is currently menstrating. I began checking her bsl an hr after bfast as after breakfast she was wanting to sleep. Noticed spikes..an hr after then decline by 2 an hr after that...
Is that what happens？ Her tiredness is a little unusual but shes not a great night sleeper and given shes menstrating i guess that could account for it...im slowly goin insane trying to work this all out....need some advice ...thnx in advance