Awareness of Prediabetes Status and Subsequent Health Behavior, Body Weight, and Blood Glucose Levels

Ibiye Owei, MD, MPH; Nkiru Umekwe, MBBS; Fatoumatta Ceesay, BS; Samuel Dagogo-Jack, MD

Disclosures

J Am Board Fam Med. 2019;32(1):20-27. 

In This Article

Methods

Study Subjects

The study subjects were participants in the POP-ABC study.[16,17] Eligibility criteria for the POP-ABC study included age 18 to 65 years, self-reported non-Hispanic white (EA) or non-Hispanic black (AA) race/ethnicity status; 1 or both biological ]parents with T2DM; no evidence of diabetes; normal FPG (<100 mg/dL [<5.6 mmol/L]) and/or normal 2hrPG (<140 mg/dL [<7.8 mmol/L]) during a 75-g OGTT; and good overall health, as previously described.[16,17] None of the participants was using any medications known to alter glucose or lipid metabolism. Enrollment in behavioral, pharmacologic, or other active weight loss program or a history of liposuction or bariatric surgery were additional exclusion criteria.[16,17] The primary outcome was the occurrence of prediabetes (IFG and/or IGT) or diabetes, defined by the ADA criteria.[4] A confirmatory test was performed within 6 weeks of each endpoint occurrence. The 75-g OGTT was the method of confirmation. All endpoints were independently adjudicated by the Institutional Data and Safety Officer (Murray Heimberg, MD, PhD). The study protocols were approved by the University of Tennessee Institutional Review Board; all participants gave written informed consent before initiation of study procedures.

Chronology and Outcome

The first subject was enrolled in September 2006 and the POP-ABC study ended in February 2012 after the final follow-up visits.[16,17] During 5.5 years of follow-up (mean, 2.62 years), 101 of 343 participants developed incident prediabetes.[17] Per the study protocol, a copy of the confirmatory OGTT result was provided to all participants reaching the endpoint. However, no intervention or counseling was provided, as POP-ABC was a purely natural history study. In September 2013, 18 months after close-out of the POP-ABC study, funding became available for a continuation study, the PROP-ABC, whose goal is to provide intensive lifestyle intervention to the POP-ABC participants with incident prediabetes (ClinicalTrials.gov Identifier NCT02027571). Eligibility for PROP-ABC thus was limited to the original POP-ABC participants, all of whom were invited to join the new study. Interested participants underwent a standard OGTT, anthropometry, and clinical examination, as part of the baseline reenrollment procedures. To test the hypothesis that awareness of incident prediabetes status triggers self-directed health behaviors that improve metabolic endpoints, we compared the temporal trends in OGTT, anthropometric, and lipid data between the end of POP-ABC and the initiation of PROP-ABC study in participants with incident prediabetes during the POP-ABC phase and an age-, sex-, and ethnicity-matched control group. We also compared changes in self-reported dietary and physical activity behaviors between the 2 groups of participants.

Figure 1 summarizes the time intervals from the beginning until the end of the POP-ABC study to rescreening for the extension PROP-ABC study.

Figure 1.

Study design and time intervals of data collection. Prediabetes outcome was assessed after ~5 years of follow-up of initially normoglycemic POP-ABC participants. Eighteen months later, POP-ABC study participants were rescreened for a newly funded extension PROP-ABC study. The present report compares the 18-month interval changes in glycemic and other measurements between participants who developed prediabetes during POP-ABC study and those who remained normoglycemic.

Assessments

Participants arrived at the University of Tennessee General Clinical Research Center after an overnight fast to undergo physical examination and scheduled assessments. Height was recorded using a stadiometer, weight was measured with a digital scale (Tanita WB-300 Plus Digital, Arlington Heights, IL), and body mass index (BMI) was calculated as weight (kg) divided by the square of the height in meters. A Gulick II tape was used to measure waist circumference, as previously described.[16,17] Usual food intake was captured using the Food Habits Questionnaire (FHQ)[18] and habitual physical activity was recorded using the Modifiable Activity Questionnaire (MAQ),[19] as previously described.[20] The responses to the MAQ were converted to metabolic equivalent (MET) based on the intensity of the reported activities and expressed as MET-hours/week.[20] A standard OGTT was initiated between 0700 and 1100: venous blood specimens for glucose and insulin measurement were obtained before (0 minutes) and at 30 minutes and 120 minutes after ingestion of 75 g flavored glucose (Trutol 75; Custom Laboratories, Baltimore, MD).

Biochemical Measurements

Plasma glucose was measured with a glucose oxidase method (Yellow Spring Instruments Co., Inc., Yellow Spring, OH). Plasma insulin levels were measured immunochemically in our Endocrine Research Laboratory, using commercial enzyme-linked immunosorbent assay kits. HbA1c and fasting plasma lipid profiles were measured in a contract clinical laboratory.

Statistical Analysis

Data were reported as means ± SEM. Differences between defined groups were analyzed using unpaired t tests for continuous variables and χ 2 test for categoric variables. Interval changes in glycemic, anthropometric, and behavioral measures between the 2 defined testing periods were analyzed using paired t tests. General linear regression models were used to analyze the relationship between temporal changes in anthropometric and metabolic variables. All statistical analyses were performed with the use of SAS statistical software, version 9.3 (SAS Institute Inc., Cary, NC).

processing....