Hi @ alphabeta,
I have been on insulin for 51 years and done the once daily, twice daily, MDI ( basal insulin once or twice daily plus short-acting insulin before each meal) regimes and am currently on an insulin pump.
On the pump I can alter the programming for basal and bolus doses plus the Insulin:carb ratio and Insulin Sensitivity Factor. These latter two readings vary between breakfast and evening times.
So I wonder whether the Humalog dose in the morning needs to be calculated differently for carbs than in the evening?
Also if you google Humalog profile pictures you can see when Humalog reaches its peak (blood sugar lowering action). It appears to do so at about 2 hours after injection but there will be variation from person to person. So the peak blood sugar from your breakfast may or may not coincide with the insulin peak. It is does not, then the blood sugar peak might precede the insulin peak and you record a high blood sugar.
The other thought is whether the Lantus dose is sufficient. I found that if my BSL on waking was in range then the long-acting dose of insulin on my past MDI regime was sufficient for me. If the BSL was high then it was likely that my2 hour post-prandial BSL was also.
Finally, some of us have the Dawn effect, where the release of hormones at about 4 am causes relative increase in insulin resistance in the hours that follow. Again a possible reason for higher bsl with the same carbs and the same Humalog dose.
If I exercise vigorously an hour or two before breakfast, the exercise caused my BSL to rise, due to adrenaline causing my liver to release stored glucose. That meant waiting for the effect of exercise some hours later before my insulin was working better.
So I would need to be doing walking or similar mild exercise for 4 hours before to ensure my bsl was better after exercise.
Your response to exercise could be quite different.
