Before revision:  However, some five-year outcomes, such as glycosylated hemoglobin (A1C) , are over 40 %DIF < missing data.
After revision:  However, as usual in longitudinal medical studies, there is a significant amount of missing data in the outcome variables. For example, 40 percent of glycosylated hemoglobin (A1C) , are over 40 %DIF < missing data.