Identifying Risk for Diabetes and Heart Disease in Women
Condition: Obesity; Insulin Resistance; Triglycerides; Diabetes
MeSH terms: Heart Diseases; Diabetes Mellitus; Insulin Resistance
Study type: Observational

Summary: 
      Background:

      - Rates of diabetes and heart disease in women are increasing. Early recognition of risk
      could help women live longer and healthier lives. Race and ethnicity may affect the best
      kinds of tests to use to screen for these conditions. Researchers want to compare risk
      factors for diabetes and heart disease in African, African-American, and white women. Doing
      so may help identify the most effective screening test for each group. This study will look
      at healthy African, African-American, and white women who are federal employees and
      contractors.

      Objectives:

      - To study risk factors for diabetes and heart disease in African, African-American, and
      white women.

      Eligibility:

        -  Healthy African, African-American, and white women between 30 and 65 years of age who
           are federal employees or contractors.

        -  For this study, African women must be born in Africa and have immigrated to the United
           States, and report that both parents are Africans. African-American women must
           self-identify as African-Americans, born in the United States, and have parents who both
           self-identify as African-American born in the United States. White women must
           self-identify as white and have parents who also self-identify as white.

      Design:

        -  Participants will have four visits to study their risk factors for diabetes and heart
           disease.

        -  The first visit is a screening visit. Participants will be screened with a physical exam
           and medical history. Blood and urine samples will be collected. They will also have an
           EKG test. Participants will also be shown how to fill out a 3-Day Food Record and wear
           an activity monitor called an accelerometer. The food record will keep track of how much
           participants eat for 3 consecutive days, including 1 non-working day. The accelerometer
           device will be worn for 3 days to monitor movement.

        -  At the second visit, participants will have blood tests, an oral glucose tolerance test,
           and body fat measurements. They will also fill out questionnaires, review the food
           record, and have two imaging studies.

        -  At the third visit, participants will have a longer glucose tolerance test. During the
           test, participants will receive both glucose and insulin and blood samples will be
           collected over several hours. Participants will receive lunch at the clinical center
           after the test.

        -  At the fourth visit, participants will have a meal test. They will fast for 12 hours
           before the test. Participants will eat a specific meal and have blood samples taken
           during and after they eat.

        -  Participants will discuss the results of these tests with the study doctors.
    

Detailed description: 
      African-American women experience disproportionately high rates of conditions related to
      insulin resistance, specifically type 2 diabetes (T2D) and cardiovascular disease (CVD). In
      Africa, T2D and CVD have also become leading causes of death for women. Early recognition of
      risk and the implementation of preventive measures could improve both quality of life and
      longevity as well as decrease health care expenditures. However, screening tests for the
      early detection of T2D and CVD were developed several decades ago in large studies with
      mostly white participants. Emerging evidence suggests that there are racial differences in
      the ability and importance of various risk factors to predict the development of diabetes and
      CVD. Consequently tests used to screen for T2D and CVD are often not effective in women of
      African descent. Thus, women of African descent lose the opportunity and benefit of early
      intervention.

      Designing tests to determine risk for T2D and CVD in women of African descent requires an
      appreciation of why current tests do not work. Screening tests to detect risk for T2D and CVD
      usually rely on the observation that insulin resistance is associated with increased hepatic
      fat, high fasting glucose and high triglyceride (TG) levels. However, while insulin-resistant
      white women usually have high liver fat, high fasting glucose and high TG levels,
      insulin-resistant African-American women often have normal TG levels, normal fasting glucose
      and low hepatic fat. Therefore, these tests routinely fail to detect risk in African-American
      women.

      The relationship between TG levels to insulin resistance, hepatic glucose production and
      liver fat has not been studied in African women. To improve diagnosis, we propose a study of
      race differences in TG levels, fasting glucose levels and hepatic fat comparing 3 groups of
      women who are federal employees or contractors: African-American African (born in subSaharan
      Africa and immigrated to the United States) and white. This design ensures all enrollees will
      have health insurance, a similar work environment and a comparable distribution of position
      (i.e. scientific, administrative, support). Analyses to detect differences in diet, physical
      activity and other psychosocial factors will be undertaken.

      There will be 4 outpatient visits for 360 non-diabetic women (120 African-American, 120
      African and 120 white, aged 25 to 65 years, BMI 20 to 45 kg/m2) enrolled. At Visit 1, a
      medical history, physical exam and screening labs will be done. Participants will record food
      intake and monitor physical activity wear an activity monirot (accelerometer) during a 7-day
      period between visits. At Visit 2 an oral glucose tolerance test will be performed. Studies
      to examine body fat content and distribution will also be done. At Visit 3, insulin
      resistance will be measured with an intravenous glucose tolerance test. At Visit 4, breakfast
      will be eaten with blood samples taken before and after the meal.

      In addition to the 4 outpatient visits described, there will be an optional overnight stay
      the evening before visit 3 for 60 women (30 African descent and 30 white). The purpose of
      this smaller study is to determine if race differences in the production of glucose by the
      liver contribute to race differences in fasting glucose levels. Eligible women will be in
      good health, between 25 and 50 years of age and have a BMI 25-45kg/m2.

      This study will be the first time (a) TG levels in African immigrants are compared to
      African-American and white women (b) hepatic glucose production is assessed by race, and (c)
      the relationship of TG to insulin resistance, liver fat, body fat distribution, diet,
      physical activity and psychosocial factors are examined in these 3 groups of women under
      similar metabolic and economic conditions. While failure of screening tests means a lost
      opportunity for early intervention, effective screening tests can change outcomes, improve
      lives and minimize health care expenditures. This protocol is building a foundation on which
      effective screening tests for diabetes and heart disease can be built.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Women-Federal Employees and Contractors@@@@@@
      
Keywords: Women; Diet; Obesity; African; Physical Activity; Natural History