Differences in participant classification and intervention effects based on HbA1C and fasting plasma glucose among a community sample of African Americans

Lovoria B Williams¹*, Jeannette O Andrews², Stephen W Looney³, Andrea M. Kriska⁴ and Janie Heath⁵

Received: November 16, 2018;   Published: November 26, 2018

DOI: 10.32474/ADO.2018.01.000122

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Abstract

Since 2010, the American Diabetes Association has endorsed both HbA1C (A1C) and fasting plasma glucose (FPG) to determine diabetes risk. Given the discordance between classifications based on FPG and A1C and higher A1C levels among African Americans (AAs) than whites, we sought to examine the prevalence of normoglycemia, prediabetes, and diabetes among a community sample of adult AAs (n=704) screened for enrollment in a randomized Diabetes Prevention Program (DPP). We conducted a retrospective analysis to estimate the degree of discordance between risk categories based on FPG and A1C and examine the risk factors that predicted A1C and FPG levels. To determine differential effects on risk categories defined using FPG and A1C, we examined the effects of the program on the measures at 12 weeks post-intervention among the intervention arm participants.

The tests revealed different prevalence levels at baseline: A1C, 36.2% normoglycemia, 52% prediabetes and 11.8% diabetes; FPG, 81.1%, 16.8%, and 2%, respectively. There was discordance among A1C and FPG and among the risk categories (p<0.001). Both final regression models included age and waist circumference as predictors. For FPG, additional predictors were family history of diabetes and male gender. Post intervention, only those classified in the prediabetes category defined in terms of either test demonstrated intervention effects. Screening test choice results in different sample composition; both A1C and FPG respond to intervention effects among individuals classified in the prediabetes group only. These results have implications for research and clinical practice.

Keywords: HbA1C; Fasting plasma glucose; Community based; Screening; African Americans; Prediabetes

Abbreviations: DPP: Diabetes Prevention Program; FPG: fasting plasma glucose; ADA: American Diabetes Association; ARIC: Atherosclerosis Risk in Communities

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