In some studies, threshold scores on these instruments were also used to identify categories of depression severity (mild, moderate, severe) or depression caseness (absent/present) that were studied in relation to glycemic control. In a similar fashion, glycemic control was sometimes used as the independent or grouping variable (e.g.,a mean split of the GHb observations), and the groups were statistically compared for differences in the frequency or severity of depression. Lastly, studies were included that reported, in the context of a randomized clinical trial (RCT), the pretreatment association of depression with glycemic control and/or the correlation of pre- to posttreatment change in depression or GHb levels with, respectively, pre- to posttreatment change in GHb or depression levels.