The amount of sugar found in a glass of wine varies depending on the type of wine served and how it was processed. Dry wines have a lower amount of residual sugar content, while semisweet and sweet wines have a higher sugar content.
An extra-dry wine, such as a pinot grigio from Italy, can have a residual sugar content of less than 1 gram in a 5-ounce serving. A semisweet wine, such as a California white zinfandel, can have up to nearly five times the sugar content of an extra-dry wine. Sweet wines have the largest sugar content of all wine types and are typically served in 2- to 3-ounce portions. A 2000 Quinta de Roriz Vintage port wine, for example, can have up to 6 grams of sugar in a serving of only 2 ounces.