The easiest and cheapest thing is to mix your own with some bulk maltodextrin. You can add sodium citrate if you need electrolytes. I buy Now Dextrose or Carbogain off of Amazon (8 or 10 pounds) and it usually comes to around $.20 per ounce. A tub last me forever.
Gatorade powder costs even less and is basically maltodextrin. I use a little in my bottles for taste but can’t take full strength Gatorade so I mix it with plain maltodextrin.
I’m not a doc and this isn’t medical advice but I personally wouldn’t worry about a .1 out of range on one single test. What is the margin of error on the test? How much do these tests vary if you tested every day for a week? If I were concerned, I’d do whatever my doc says to do.