1 unit increase in the short
acting is also 1 unit more increase in the
long acting. This is perhaps not exactly what you need as your sugars say 6 hours from now are not running high.
Also, the premixes are usually used once a day to two times a day (because of the amount of the long acting insulin), most type 1's are on 3 times a day or more therapy which has proven to be most optimal in control.
Hope this helps.