No one knows the exact cause of diabetes. Most people who get type 2 diabetes are older, but now younger people are being diagnosed with it. Like many young people, you are probably thinking, "Why should I be concerned about diabetes?" The truth is that both the Center for Disease Control and the American Diabetes Association are quite alarmed about the increase in type 2 diabetes among young people. Information gathered in the 1990s showed a rapid increase in type 2 diabetes in children. During the 2000s, this trend has continued. Scientists who study diabetes are finding that 85 percent of the children who are diagnosed with type 2 diabetes are overweight. But that is just one reason for the increase. Children are at risk for type 2 diabetes if they are inactive, have a family history of diabetes, or are from African-American, American-Indian, or Asian-American families.
The decades mentioned may be spelled in two different ways. A more formal and traditional one would add the apostrophe between the last number and the letter s: 1990's instead of 1990s.
I have added the hyphen between words in the last line because they function as adjectives in this sentence. If they were functioning as nouns, then the hyphen wouldn't be necessary. Compare:
African Americans have the right to demand better conditions...
African-American families have the right...