U.S. Department of Health and Human Services

 Contact Info

Tel: 602-200-5206
Email: wknowler@phx.niddk.nih.gov

 Select Experience

  • Chief, Diabetes Epidemiology and Clinical Research SectionNIDDK1979-present
  • Staff Associate/Staff PhysicianNIDDK1975-1979
  • Resident in Preventive MedicineHarvard School of Public Health1974-1975
  • Intern in internal medicineFaulkner and Lemuel Shattuck Hospitals, Boston1973-1974
  • StatisticianSheller-Globe Corporation (chemical manufacturing)1966-1969
  • DrPHHarvard School of Public Health1980
  • MDHarvard Medical School1973
  • MPHHarvard School of Public Health1973
  • BAUniversity of Iowa1968

 Related Links

  • Clinical Research
  • Epidemiology/Population Sciences
  • Genetics/Genomics
  • Social and Behavioral Sciences
Research Summary/In Plain Language

Research Summary

Research Goal

Our goal is to advance knowledge of causes of type 2 diabetes, obesity, and their complications, especially among Southwestern U.S. minority populations, with the aim of improving prevention and treatment of these conditions.

Current Research

My work advances knowledge about prevention and treatment of diabetes, obesity, and their complications through research using methods of epidemiology, genetics, and randomized clinical trials.  My major research programs have been a 43-year longitudinal population study of type 2 diabetes and related conditions and two multi-center randomized clinical trials – the Diabetes Prevention Program (DPP) with its follow-up study, the Diabetes Prevention Program Outcomes Study (DPPOS), and Action for Health in Diabetes (Look AHEAD). 

The longitudinal population study has had world-wide impact in elucidating risk factors for type 2 diabetes and its complications and in establishing diagnostic criteria.  Other findings concern the long-term effects of maternal diabetes in pregnancy on the offspring and problems related to obesity and type 2 diabetes in children.  Our research has expanded knowledge of the genetic bases for type 2 diabetes and obesity.  The genetic studies have been extended through participation in a multi-center study of genetic susceptibility to diabetic nephropathy – the Family Investigation of Nephropathy and Diabetes (FIND).

DPP and DPPOS showed that the development of type 2 diabetes could be greatly reduced or delayed in high-risk adults either by a behavioral weight-loss intervention or the drug metformin.  The DPPOS is examining long-term durability of diabetes prevention/delay and its effects on other health outcomes including microvascular complications, cancer, and cardiovascular disease.  In Look AHEAD, a behavioral weight-loss intervention in adults with type 2 diabetes reduced cardiovascular disease risk factors (but not events), health care costs, and the development of advanced kidney disease.

Our main current projects include continuing and analyzing the clinical trials, expanding our studies of mothers and children, and analyzing epidemiologic and genetic data (including genome-wide association and whole exome sequencing data).

Applying our Research

Results of the longitudinal population study have had widespread influence on research and practice related to type 2 diabetes, and have been instrumental in development of national and international criteria for diagnosing diabetes and classifying risk conditions.  The DPP results are widely implemented in clinical practice with the support of several health care organizations and payers, including the U.S. government’s Indian Health Service and Centers for Medicare and Medicaid Services.

Need for Further Study

Despite substantial progress, the environmental, behavioral, and genetic causes of type 2 diabetes, obesity, and their complications are only partially understood.  Similarly, while we have shown that lifestyle interventions and drug treatments have substantial health benefits, they can be difficult for health practitioners to administer and for individuals to follow.  Their effects on health risks are sometimes modest, and their long-term durability is uncertain.  Therefore, we need better knowledge of the risk factors for these diseases and how that knowledge can be translated into better prevention and treatment strategies.