Hi
What type is mum, and what is she on? That would help us to help you. HOwever, some thoughts are-
One of the most likely reasons she needs more in the morning is because diabetics (esp type 2's, often type 1's) and even non diabetics can be insulin resistant in the morning. Therefore what you eat needs more insulin to tackle it and therefore keep you bg from going too high. They believe this to be related to the counter regulatory hormones needed to get us 'up' in the morning (cortisol, glucogen etc). This also causes waking sugars higher than what you went to bed with and has the lovely moniker of Dawn Phenomenon.
In older people, I also feel that they cut the insulin at night to less than say a someone who considers a need to be well controlled would accept. I suspect this is to prevent overnight hypos.
It might also be that most of the food consumed during the day needs to be covered by the morning jag and what is eaten at night/overnight fasting is covered by less amounts injected at night
Hope this helps
