Table 3—

Distribution of FPG and 2-h (OGTT) plasma glucose diagnostic categories, and mean A1C, in U.S. adults aged ≥20 years, NHANES 2005–2006

Diagnostic category based on FPGDiagnostic category based on 2-h glucoseDistribution across 2-h glucose categories by FPG diagnostic categoryDistribution across FPG and 2-h glucose diagnostic categoriesA1C (%)
Undiagnosed diabetesUndiagnosed diabetes91.0 (74.0–97.3)2.3 (1.3–4.0)7.04 (6.37–7.70)
IGT1.4* (0.1–12.7)0.0*
Normal7.6* (2.3–22.2)0.2* (0.1–0.7)
IFGUndiagnosed diabetes8.5 (5.9–12.2)2.2 (1.5–3.3)5.80 (5.71–5.88)
IGT31.3 (24.3–39.2)8.1 (5.9–11.0)5.66 (5.60–5.73)
Normal60.2 (52.6–67.3)15.7 (13.7–17.9)5.50 (5.46–5.55)
NormalUndiagnosed diabetes0.6* (0.3–1.5)0.4* (0.2–0.9)
IGT8.9 (6.4–12.2)5.7 (4.1–7.8)5.44 (5.39–5.50)
Normal90.5 (87.2–93.0)57.7 (53.2–62.0)5.28 (5.25–5.30)
Diagnosed diabetes7.7 (6.7–8.8)
Total100.0
  • Data are % (95% CI) except for A1C values, which are means (95% CI).

  • *

    * Relative standard error >30%: the confidence interval is wide, relative to the size of the estimate.

  • Rounds to zero.

  • n < 30. Undiagnosed diabetes determined by either FPG ≥7.0 mmol/l or 2-h plasma glucose ≥11.1 mmol/l. IFG, FPG 5.6–7.0 mmol/l; IGT, 2-h plasma glucose 7.8–11.1 mmol/l; diagnosed diabetes determined by self-report on interview.