William Knowler, M.D., Dr.P.H., Scientist Emeritus

Scientist Emeritus:
Phoenix Epidemiology & Clinical Research Branch
Scientific Focus Areas: Clinical Research, Epidemiology, Genetics and Genomics, Social and Behavioral Sciences
Clinical Trials
Open studies conducted by NIDDK Principal Investigators appear below. Study statuses may include the following:
- Open: Recruiting - Currently recruiting participants and open to everyone who meets eligibility criteria.
- Open: Active, Not Recruiting - Participants are receiving an intervention or being examined, however new participants are not being recruited or enrolled.
- Open: Enrolling by Invitation - People in a particular population were selected in advance and invited to participate. The study is not open to everyone who meets the eligibility criteria.
- Open: Available for Expanded Access - Patients who are not participants in the clinical study may be able to gain access to the drug, biologic, or medical device being studied.
Studies Seeking Patients
Diabetes Prevention Program Outcomes Study
The Diabetes Prevention Program (DPP) was a multi-center trial examining the ability of an
intensive lifestyle or metformin to prevent or delay the development of diabetes in a high
risk population due to the presence of impaired glucose tolerance (IGT, 2 hour glucose of
140-199 mg/dl). The DPP has ended early demonstrating that lifestyle reduced diabetes onset
by 58% and metformin reduced diabetes onset by 31%.
DPPOS (2002-2013) is designed to take advantage of the scientifically and clinically valuable
DPP participants. This group of participants is nearly 50% minority and represents the
largest at risk population ever studied. Clinically important research questions remain that
focus on 1) durability of the prior DPP intervention, 2) determination of the clinical course
of precisely known new onset diabetes, in particular regarding microvascular disease, CVD
risk factors and atherosclerosis, 3) close examination of these topics in men vs women and in
minority populations.
The major aims of DPPOS-3 (2014-2025) take advantage of the long-term randomized exposure of
the study cohort to metformin and the aging of the DPPOS cohort. The metformin exposure and
high degree of study retention and adherence (~85% of the DPPOS cohort continues to attend
annual and mid-year visits) allows DPPOS-3 to examine the long-term effects of metformin on
cardiovascular disease (CVD) and cancer outcomes, outcomes of great clinical interest and
import.
The trial is Open with a status of Active, not recruiting.
Investigator: David M. Nathan, MD