Background: There is limited data on the
prevalence of diabetes, prediabetes, and metabolic
syndrome in the rural areas of the Philippines.
Methods: A survey was done to determine the
prevalence of these three conditions in the rural
town of San Juan, Batangas.
Results: Community members did not
understand the role of randomization. They felt that
it was wrong for healthy people to undergo medical
evaluations while people with known diabetes and
hypertension were not automatically enrolled. Most
of the subjects who presented for the survey were
family members of the individual who had been
originally randomly selected. As a group, these
“non-selected” volunteers had significantly higher
cardiac and metabolic risk factors that those subjects
who had been randomly selected.
Conclusions: Volunteer bias hampered the
accurate determination of the true prevalence of
these conditions despite our best efforts at ensuring
random selection of participants. This experience
provides a real world example of how socioeconomic
realities in the community make volunteer
bias difficult to avoid in a rural resource-limited
area. Recommendations for ad-dressing this
problem are provided.