Table 2.
The effect of 14-weeks of KDPWHE, WHEY, or CON supplementation in adults with type-2 diabetes mellitus on whole-body and skeletal-muscle glucoregulatory phenotype responses: haemoglobin A1c, basal and insulin-stimulated glucose clearance rate and, nutrient delivery to skeletal muscle microvasculature, and sarcoplasmic membrane GLUT4 content and translocation.
| Parameter, condition | Within-Group Baseline-Adjusted Changea |
Baseline-Adjusted Treatment-Group Contrast Effect Size Statisticsc |
||||
|---|---|---|---|---|---|---|
| Treatment (n) | Week 15-0 Change in % (90%CL)b | Treatment Contrast | Estimate in % (90%CL)c | Standardized difference (90%CL)d | Magnituded | |
| Glucose clearance and glycaemic control | ||||||
| Glucose clearance rate, insulin stimulated | CON (12) | 20 (3, 41) | WHEY-CON | -2 (-22, 23) | -0.41 (4.1, -4.3) | Unclear |
| WHEY (12) | 18 (0.4, 39) | KDPWHE-CON | 24 (2, 55) | 4.4 (0.3, 10.4) | Slight to very large | |
| KDPWHE (11) | 49 (26, 75) | KDPWHE-WHEY | 26 (0, 59) | 4.9 (0.0, 11.1) | Slight to very large | |
| [HbA1c], basal | CON (12) | -18 (-23, -12) | WHEY-CON | 16 (-5.4, 28) | 2.0 (0.7, 3.4) | Slight to moderate |
| WHEY (12) | -4.2 (-12, 3.9) | KDPWHE-CON | 5.8 (-4.1, 17) | 0.7 (-0.5, 2.0) | Slight to small | |
| KDPWHE (11) | -13 (-20, -5.5) | KDPWHE-WHEY | -9.1 (-19, 1.5) | -1.1 (-2.2, 0.2) | Slight to small | |
| Skeletal muscle microvascular nutrient delivery and sarcoplasmic GLUT4 translocation | ||||||
| mBF, insulin stimulated | CON (12) | 39 (28, 52) | WHEY-CON | -3 (-30, 33) | -0.07 (-0.82, 0.66) | Unclear |
| WHEY (10) | 35 (-1.5, 84) | KDPWHE-CON | 46 (16, 83) | 0.87 (0.35, 1.39) | Slight to large | |
| KDPWHE (9) | 103 (63, 152) | KDPWHE-WHEY | 51 (5, 116) | 0.94 (0.11, 1.77) | Slight to large | |
| mBV, insulin stimulated | CON (10) | 2.2 (-0.0, 4.6) | WHEY-CON | -3 (-9, 3) | -0.08 (-0.23, 0.06) | Trivial |
| WHEY (11) | -1.2 (-6.7, 4.7) | KDPWHE-CON | -3 (-10, 4) | -0.08 (-0.25, 0.09) | Unclear | |
| KDPWHE (8) | -1.2 (-7.7, 5.9) | KDPWHE-WHEY | 0 (-8, 9) | 0.00 (-0.20, 0.20) | Trivial | |
| GLUT4, basal | CON (10) | -3.7 (-15, 8.0) | WHEY-CON | -1 (-17, 18) | -0.05 (-1.00, 0.90) | Unclear |
| WHEY (9) | -4.6 (-18, 9.0) | KDPWHE-CON | -5 (-16, 9) | -0.29 (-1.02, 0.45) | Unclear | |
| KDPWHE (9) | -9.1 (-17, -1.6) | KDPWHE-WHEY | -4 (-18, 12) | -0.24 (-1.06, 0.59) | Unclear | |
| GLUT4, insulin stimulated | CON (10) | 19 (2.5, 36) | WHEY-CON | 3 (-12, 20) | 0.13 (-0.70, 0.97) | Unclear |
| WHEY (9) | 10.1 (-0.6, 21) | KDPWHE-CON | 18 (0, 39) | 0.87 (-0.03, 1.76) | Slight to large | |
| KDPWHE (9) | 25 (13, 37) | KDPWHE-WHEY | 15 (-1, 34) | 0.73 (-0.07, 1.53) | Slight to large | |
Refer to Fig. 1 for plots of raw unit point data and distribution statistics, SM Data 1 for detailed statistics, raw measurement units, raw unit point and change-score mean and SD.
Data are least-squares mean Week 15-0 change score in percent with 90% confidence limits (90%CL) for single point observations or insulin-stimulated values, where the latter is the insulin-stimulated (measured during isoglycaemic clamp) minus baseline (measured pre-clamp) difference score. Data are baseline-covariate adjusted values.
Effect statistics are baseline-adjusted estimates of the treatment effects on the week 15-0 change score with 90%CL expressed as percent.
Magnitude of effect estimates were interpreted from the lower and upper CLs, consistent with an alpha of 0.05 (maximum error rate of 5%) for rejection of substantial (superiority) hypotheses, referenced against the smallest effect threshold. The thresholds for interpreting effect magnitudes are based on the modified Cohen d scale, where effects <0.2SD are slight (or trivial if the 90%CL sits within thresholds for small negative and small positive), >0.2SD are small, >0.6SD moderate, >1.2SD large, >2.0SD very large, and >4.0SD exceptional. Effect magnitudes for the two clinically-defined variables (GCR, HbA1c) are factors of magnitude relative to the smallest important clinical effect size (SIE) (GCR, 5.4% [51]; HbA1c, 5.5 mmol HbA1c per mole of total haemoglobin which translates to 8.7% of the pooled baseline HbA1c concentration 63.1 mmol/mol). The clinical factors use the same scale of effect size qualifier, but the value for the SIE replaces the Cohen d threshold for small differences, with the threshold for small being an effect size/SIE>1.0, with larger effect sizes increasing in step magnitude by factors of the SIE of x3 (moderate), x6 (large), x10 (very large), and x20 (exceptional), respectively [50,57].Further details about our approach to evaluating sampling uncertainty is described in the Materials and Methods section.CON, non-protein isocaloric control; KDPWHE, keratin-derived protein with whey protein blend; WHEY, whey protein isolate; microvascular blood flow (mBF); vasodilation (blood volume, mBV); glucose transporter 4 (GLUT4). Insulin stimulated is the insulin minus baseline score difference.