Study Population and Recruitment
Adults at increased risk for type 2 diabetes
(prediabetes), defined as meeting
two of three glycemic criteria for prediabetes
established in 2010 by the American
Diabetes Association (fasting
plasma glucose [FPG] 100–125 mg/dL
[5.5–6.9 mmol/L]; 2-h postload glucose
[2hPG] after 75-g glucose load 140–199
mg/dL [7.7–11.0 mmol/L]; hemoglobin
A1c 5.7–6.4% [39–46 mmol/mol]), are
eligible for enrollment in D2d. Because
of the requirement to meet at least two
of these criteria to be considered at risk
for diabetes, it is expected that D2d
participants will be at relatively high
risk for progression to diabetes. Other
inclusion criteria and major exclusion
criteria are shown in Table 1. The
screening process is staged in two visits.
At the first screening visit, all nonglycemic
eligibility criteria are assessed, and
FPG and hemoglobin A1c are measured
at the local laboratory to assess preliminary
eligibility. If FPG and hemoglobin
A1c results are within range based on a
site-specific algorithm, the volunteer
proceeds to the second screening visit.
At that visit, which also serves as the
baseline visit for participants who
qualify, a 75-g oral glucose tolerance
test (OGTT) is performed for FPG, 2hPG,
and hemoglobin A1c, which are analyzed
by the central laboratory.