About Diabetes Data

Tracking diabetes involves collecting data about the number individuals told that they had diabetes while participating in the Behavioral Risk Factor Surveillance System (BRFSS) survey.

This page provides general information about diabetes data and measures developed by the Iowa Public Health Tracking program. Contact Us for more information about these data.

Information on this page:

What is the source of the data?

  • The Diabetes data displayed here are collected through the Behavioral Risk Factor Surveillance System (BRFSS). BRFSS is the nation’s premier system of telephone surveys that collect state data about health risk behaviors, chronic health conditions, and use of clinical preventive services among adult U.S. residents.

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How does BRFSS collect data?

  • BRFSS invites a randomly selected sample of Iowan adults to participate in the telephone survey. Recent surveys have included both adults who have landline telephones and cell phone users, and have had between 6,000 and 7,700 participants. All responses are weighted to the entire Iowan population so that weighted results are intended to capture the experience of the entire state.

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Which questions were asked to collect data on diabetes?

  • People who took part in BRFSS were asked the question, "Has a doctor, nurse, or other health professional ever told you that you had diabetes?" If they said "yes," they were counted as having diabetes. If they were female and said, "Yes, but only during pregnancy," they were counted as not having diabetes. Gestational diabetes or diabetes during pregnancy is different than having a diabetes diagnosis. Those who responded "No" or "No, prediabetes or borderline-diabetes" were not counted as having diabetes.

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Which questions were used to collect data on pre-diabetes?

Two questions on pre-diabetes were included in the BRFSS questionnaire.

  • The first question asked respondents, “Have you ever had a test for high blood sugar or diabetes within the past three years?” Those who answered "yes" were counted as having had a recent pre-diabetes test.
  • The second question asks respondents, “Have you ever been told by a doctor or other health professional that you have prediabetes or borderline diabetes?” If they said "yes," they were counted as having pre-diabetes. If they were female and said, "Yes, but only during pregnancy," they were counted as not having pre-diabetes. Those who responded "No" were also not counted as having pre-diabetes.

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What time period was the data collected?

  • The Diabetes question was asked in the BRFSS Core section every year from 2011-2017.
  • The prediabetes questions were asked in the 2011, 2012, 2013, 2014, 2016 and 2017 versions of the BRFSS questionnaire.

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Can I compare pre-2011 BRFSS data to post-2011 BRFSS data?

  • No, due to changes in data collection and analysis methodology; data from 2011 and later should not be compared to data from before 2011. Earlier versions of the BRFSS survey only contacted people with landline telephones. Beginning in 2011, BRFSS changed the collection methodology to include cell phones in its sampling frame. In addition, a new method for weighting the sample called iterative proportional fitting or raking was introduced. This methodology better allows data for population subgroups that are underrepresented in the sample to be more accurately represented in weighted estimates. The raking method allows more demographic variables to be used in creating sample weights leading to more accurate estimates.

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Where can I find more technical information about the data?

  • To explore technical information and to review the annual reports, please visit the IDPH BRFSS website.

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