Data on diabetes mellitus (type I or II) are derived from the Health Survey of the Integrated System of Social Surveys (POLS) conducted by Statistics Netherlands. Respondents are invited to state whether they suffer from diabetes. If the answer is affirmative, they are requested to answer follow-up questions, e.g. about insulin intake.
As POLS is a sample survey, the figures are subject to a margin of error. To reduce the risk of inaccurate results, a longer period (e.g. 2007/2008 or 2001/2008) is taken into account.