I've just looked at some of your past posts.
The insulin you are using is apparently
Insuman Comb 25, .(and this post is based on that)
It contains 2 types of insulin: regular soluble insulin to cover your meals and intermediate insulin to cover the glucose released from your liver between meals.
It has a very gradual onset
Insuman Comb 25 is injected subcutaneously 30 to 45 minutes before a meal
http://www.medicines.org.uk/emc/medicine/26469/spc .if you eat immediately after injecting (and it seems like that from your post)then it won't work fast enough to have a chance of covering the rise caused by the toast. .
This graph shows that it's at it's peak from 2-4 hours after injecting.
This type of insulin works best with regular meals and consistent carbohydrate intake . It doesn't work well if you eat 20g of carbohydrates for one meal, say breakfast one day and 4g the next nor if you vary the times of meals too much.
Because the insulins are pre-mixed you can't easily vary your meals from day to day.
People are advising you to cut down from one slice of toast (less than 20 g carb) but don't seem to be taking into acount the insulin that you take.. If you reduce your carbohydrates and still take the same amount of insulin, then you risk having a hypo later. However, If you reduce the insulin you may not have enough intermediate insulin to cover the glucose released between meals.
As picklebean says it is best to check 2 hours after and also before meals.
This link tells you how to adjust your insulin based on the before meal readings . Obviously you need to discuss making any alterations with your Nurse/doctor.
http://medweb.bham.ac.uk/easdec/prevent ... tures.html
.
If you have been taking your insulin immediately prior to insulin, then I would take it carefully, moving the timing of the injection before the meal back gradually since the absorption of these insulins can vary from person to person.