Table 3.
Variability and reproducibility metrics: geometric means, between- and within-subject geometric CVs, and ICCs for MMTT and AST and arithmetic means and total CVs for FSIGT
| Stimulation test parameter | Population (N) | Model predicted geometric mean (95% CI) | Geometric CV% between subjects (90% CI) | Geometric CV% within subjects (90% CI) | ICC (90% CI) |
|---|---|---|---|---|---|
| MMTT: Φtot (10−9min−1) | NGT (N = 23) | 104 (83–132) | 27.1 (14.7–51.6) | 41.4 (32–54.1) | 0.31* (0.30–0.77) |
| PDM (N = 17) | 115 (90–147) | 34.8 (24.1–51.1) | 19.6 (14.7– 26.2) | 0.753 (0.70–0.9) | |
| T2DM (N = 22) | 15 (12–20) | 57.8 (41.8–82.1) | 26.1 (20.2–33.8) | 0.814 (0.69–0.96) | |
| MMTT: Si (10−4min−1 [µU/mL]−1) | NGT (N = 23) | 5.5 (4.1–7.3) | 48.2 (34.1–69.8) | 32.6 (25.4–42.3) | 0.674 (0.521–0.874) |
| PDM (N = 17) | 2.5 (1.8–3.3) | 44 (28.4–70.5) | 35.5 (26.5–48.2) | 0.598 (0.469–0.837) | |
| T2DM (N = 19) | 1.2 (0.9–1.6) | 53.5 (26.9–121.5) | 83.2 (60.1–120.6) | 0.323† (0.034–0.772) | |
| MMTT: DI (10−13min−2 [µU/mL]−1) | NGT (N = 23) | 585 (405–845) | 42.3 (22.7–84.9) | 66.1 (50–89.6) | 0.312‡ (0.264–0.769) |
| PDM (N = 17) | 289 (197–424) | 54.4 (35.3–87.9) | 40.3 (29.9–55) | 0.633 (0.543–0.852) | |
| T2DM (N = 19) | 21 (14–31) | 67.3 (35.1–152.2) | 97.1 (69–145) | 0.36§ (0.254–0.754) | |
| AST: AIRarg (µU/mL) | NGT (N = 23) | 84 (67–106) | 38.9 (29.4–52.1) | 11.6 (9.1–14.8) | 0.914 (0.902–0.961) |
| PDM (N = 16) | 94 (73–120) | 38.9 (27.6–55.7) | 11.5 (8.6–15.4) | 0.915 (0.874–0.972) | |
| T2DM (N = 22) | 35 (28–45) | 53.7 (39.1–75.4) | 22.8 (17.7–29.5) | 0.833 (0.734–0.966) | |
| AST: AIRargMAX (µU/mL) | NGT (N = 23) | 391 (301–509) | 57.5 (42.8–79.2) | 16.6 (13–21.2) | 0.914 (0.858–0.967) |
| PDM (N = 16) | 389 (293–517) | 31.2 (22.1–44.5) | 11.2 (8.3–15) | 0.882 (0.815–0.969) | |
| T2DM (N = 22) | 84 (65–110) | 63.1 (46.6–87.9) | 13.8 (10.7–17.7) | 0.947 (0.931–0.982) | |
| AST: ISR (µU/mL) | NGT (N = 23) | 306 (226–414) | 64.1 (47.2–89.6) | 20.1 (15.7–25.7) | 0.897 (0.83–0.96) |
| PDM (N = 16) | 293 (212–406) | 34.4 (24.3–49.3) | 12.4 (9.2–16.6) | 0.88 (0.759–0.976) | |
| T2DM (N = 22) | 47 (35–64) | 79.3 (57.3–114.5) | 19.6 (15.3–25.3) | 0.928 (0.916–0.968) | |
| FSIGT: no within-subject variability estimable, total variance estimated, and analyses on arithmetic scale. | |||||
| • Mean (95% CI) CV% AIRg ([µU/mL]) × min): NGT, 915 (708–1,122), 81%; PDM, 489 (241–737), 77%; and T2DM, 10 (−201 to 222), 413%. | |||||
| • Mean (95% CI) CV% Si (10−4min−1 [µU/mL]−1): NGT, 1.9 (1.5–2.3), 60%; PDM, 1.2 (0.7–1.6), 37%; and T2DM, 0.8 (0.4–1.2) 101%. | |||||
| • Mean (95% CI) CV% DI (10−4): NGT, 1,339 (1,093–1,585), 64%; PDM, 576 (282–871), 90%; and T2DM, 9 (−242 to 261), 557%. | |||||
Exclusion of single-visit extreme value produces good reproducibility results for MMTT across all GT populations: *ICC = 0.59 (0.551–0.801) excluding single-visit extreme value (P < 0.001) from NGT (N = 22); †ICC = 0.559 (0.387–0.795) excluding single-visit extreme value (P < 0.001) from T2DM (N = 18); ‡0.527 (0.476–0.797) excluding single-visit extreme value (P < 0.001) from T2DM (N = 18); §ICC = 0.527 (0.476–0.797) excluding single-visit extreme value (P < 0.001) from T2DM (N = 18).