Hi
@Steve1885, From my experience as a T1D, not as professional advice or opinion:
Do you have the same breakfast each morning? And how old are you?
And according to the Carb to Insulin ratio you mentioned of 10g:1 unit, the calculation I made for your Novarapid dose would have been 8 1/2 Units. So I expect you thought 10 units would be heaps?
BSL measurement: I also note that the most usual time recommended to test BSLs after meals is > 90 minutes and more usually 120 minutes or 2 hours. So BSL at the 1 hour mark does not tell us (and you) enough. It could be higher at the 2 hour mark or not.
Assuming that the 2 hour result could be higher:
Possibilities: Maybe that ratio has changed if you are growing and
going through a growth spurt. growth hormones make insulin less effective.
Or you maybe unfortunately
sickening for something. Infections can increase insulin resistance, as can a recent vaccination.
Are you under any more stress than usual.? Stress causes release of more of the stress management hormone, cortisol.
And cortisol makes insulin less effective.
Exercise the day before will sometimes improve my insulin sensitivity the following day so is the opposite possible,? i.e. that you exercise most days and the day before this breakfast you did not exercise, making insulin sensitivity less than on the other days??
Insulin profile: (google pictures of insulin profiles and then look for Novo Rapid or Novarapid) We might assume from the drug company profiles of insulin, e.g. for Novarapid, that the peak activity after injection is say 3 hours but it may be sooner or later in some persons. If you usually take Novarapid 1/2 hour before the meal or even 1 hour before that can change how well or not the insulin's activity matches and subdues the blood sugar rise. So a
difference in timing of injection of Novarapid before breakfast might make a difference to the result.
Or
the brand or formulation of the cereal has changed. Did your
estimation of the carb content of the cereal include the total carbs or just the sugars, as there is some differences between the two in terms of values. Do you usually have
other things for breakfast in addition to cereal such as eggs, yoghurt etc.? These other foods may slow absorption of carbs and thus alter the time and height of the blood sugar peak. So not eating these say with this breakfast can alter the results.
How old is your insulin and how well stored? The pamphlet in with insulin states keep at between 2 and 8 degrees C unless in use, in which case the insulin remain active for 28 days of kept below 30 degrees C. Could your Novarapid have frozen at some stage or been out of the fridge > 28 days or been exposed to > 30 degrees C?
Other imponderables: BSLs can be influenced by seasons, weather, temperatures, say between summer and winter.
I hope the above gives you some things to consider.
The other suggestion is to look up mendosa.com and read up on what
Glycaemic Index (GI) and
Glycaemic Load (GL) are and look at
Glycaemic Values and at Cereals some way down under 'C'. Look for your cereal or the closest thing to it you can find. See how it compares to Oats and other cereals and see what you think. Also note that adding milk helps to lower and slow the rise in BSL from the cereal. Best Wishes and please keep posting about how you are going !!!