Any site should tell you the sugar and fiber content.
www.thedailyplate.com says this about 1 cup of sweet potato:
Nutrition Facts
Serving Size: 1 cup (200g)
Amount per Serving
Calories 180 Calories from Fat 3
% Daily Value *
Total Fat 0g 0%
Saturated Fat 0g 0%
Cholesterol 0mg 0%
Sodium 72mg 3%
Potassium 950mg 27%
Total Carbohydrate 41g 14%
Dietary Fiber 7g 28%
Sugars 13g
Protein 4g 8%
Vitamin A 769%
Vitamin C 65%
Calcium 8%
Iron 8%
Vitamin E 7%
Vitamin K 6%
Thiamin (B1) 14%
Riboflavin (B2) 12%
Niacin (B3) 15%
Vitamin B6 29%
Folic Acid (Folate) 3%
Vitamin B12 0%
Magnesium 14%
Panthothenic Acid 18%
Zinc 4%
Copper 16%
Manganese 50%
Est. Percent of Calories from:
Fat 0.0% Carbs 91.1%
Protein 8.9%