To review the literature estimating the cross-sectional prevalence of clinical depression in adults with Type 1 diabetes. Electronic databases and published references were used to identify studies published between January 2000 and June 2004, with a previous meta-analysis used to identify studies before 1 January 2000. Between January 2000 and June 2004, a further five eligible studies were identified. Only one was a controlled study using diagnostic interviewing to determine rates of depression. Taking all of the eligible studies identified by the previous meta-analysis and this search, the prevalence of clinical depression in controlled studies was 12.0% for people with diabetes compared with 3.2% for control subjects. In studies with no control group, the prevalence of clinical depression was 13.4%. There are wide-ranging differences reported in the various studies on the prevalence of depression in Type 1 diabetes. In view of the differing methods of diagnosis and small participant numbers, the results should be viewed with caution. A controlled study using diagnostic interviewing techniques to determine levels of depression is recommended to provide a clearer picture of both the prevalence and characteristics of that depression.