From the source... Verdict is Yes. Still, I'd guess the amount of sugar in the meat is negligible, compared to the amount in the sauce.
McRib Sandwich:
McRib Pork Patty, McRib Bun, McRib Sauce, Pickle Slices, Slivered Onions
McRib Pork Patty:
Pork, water, salt, dextrose, BHA and BHT and propyl gallate and citric acid (preservatives).
McRib Sauce:
Water, high fructose corn syrup, tomato paste, distilled vinegar, molasses, natural smoke flavor (plant source), food starch-modified, salt, sugar, spices, soybean oil, xanthan gum, onion powder, garlic powder, chili pepper, sodium benzoate (preservative), caramel color, beet powder.
McRib Bun:
Enriched flour (bleached wheat flour, malted barley flour, niacin, reduced iron, thiamin mononitrate, riboflavin, folic acid), water, yeast, high fructose corn syrup, contains 2% or less of the following: salt, corn meal, wheat gluten, soybean oil, partially hydrogenated soybean and/or cottonseed oils, dextrose, sugar, malted barley flour, cultured wheat flour, calcium sulfate, ammonium sulfate, soy flour, dough conditioners (sodium stearoyl lactylate, datem, ascorbic acid, azodicarbonamide,
mono- and diglycerides, ethoxylated mono- and diglycerides, monocalcium phosphate, enzymes, guar gum, calcium peroxide), calcium propionate (preservative), soy
lecithin.