| I've had lots in the last 18 years.
I know that at Dairy Queen I had a medium chocolate malt that was something like 180 carbs. Since you're on a pump, I'll let you know what I did...
I used my regular ratio for that time of the day, which was like 1:12 at the time (now it's like 1:28 since starting to lose weight). I set the bolus amount and did a dual wave for 25% up front and the rest over 2.5 hours. I drink them slowly, if you don't then maybe only 1.5 hours...?
I do the same for regular milkshakes. They're less carbs without the malt in them... | 
