1089-P: Abnormal Glucose Tolerance Consequences Depend on Etiology: Insulin Resistance vs. ß-Cell Failure

Abnormal glucose tolerance (Abnl-GT) is due to an imbalance between insulin resistance (IR) and β-cell function. Recent data from Africa suggest that β-cell failure contributes to the development of Abnl-GT more than previously recognized. Therefore in 490 African-born Blacks living in the United States (Male 64%, Age 38±10y (mean±SD), we compared the prevalence and metabolic characteristics of Abnl-GT due to IR (Abnl-GT-IR) to Abnl-GT due to β-cell-failure (Abnl-GT-β-cell-failure). Based on OGTT, Abnl-GT was defined as fasting glucose≥100 mg/dL or 2h glucose≥140 mg/dL. Visceral adipose tissue (VAT), triglyceride (TG) and 10y-Cardiovascular Risk-Score (CVD-Risk-Score) were measured. The cohort was divided into quartiles of HOMA-IR and quartiles of Matsuda Index. IR was defined by thresholds at the upper quartile of HOMA-IR (≥2.05) or the lowest quartile of the Matsuda index (≤2.97). Diagnosis of Abnl-GT-IR required both Abnl-GT and IR. Abnl-GT-β-cell failure was defined as Abnl-GT without IR. Abnl-GT occurred in 38% (181/490) of Africans. Of the Africans with Abnl-GT, insulin resistance occurred in 38% (68/181) and β-cell-failure occurred in 62% (113/181) of the Africans. Compared to Africans with Abnl-GT-β-cell-failure, Africans with Abnl-GT-IR had higher BMI (31.0±4.5 vs. 27.4±3.8 kg/m²), VAT (160±72 vs. 111±65 cm²), TG (106±52 vs. 77±39 mg/dL) (all P<0.001) and CVD-Risk-Score (26±24 vs. 19±17) (P<0.05). Independent of whether IR was defined by HOMA-IR or Matsuda index, results were similar. Alcohol intake was higher in the Abnl-GT-IR group (P=0.05), but other potential confounders such as years in the United States, income, education, sedentary behavior and fiber intake did not differ. Overall, Abnl-GT-IR was less common than Abnl-GT-β-cell-failure, but the metabolic profile was worse in Abnl-GT-IR. To determine the clinical course for these two types of Abnl-GT, prospective study design needs to include methodology to both diagnose Abnl-GT and elucidate the cause.