Hello, yes dextrose is a sugar, it metabolizes nearly as fast as glucose. So it has a high GI. (By the way, Glycemic Index just tells us how fast insulin will act on foods, not how much insulin is released. There's a new chart called Insulin Index that will tell us this. Just thought I'd throw that in). Honestly, if taking potassium just plain makes you feel better then by all means take the one containing dextrose. One carbohydrate won't make or break your diet.