Table 1.
Blood glucose, plasma insulin and plasma glucagon concentrations following control drink (C), 30 g whey protein drink (P), 30 g glucose drink (G) and 30 g whey protein plus 30 g glucose drink (GP) ingestion.
| Younger Men | Older Men | p Value | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| C | P | G | GP | C | P | G | GP | Age | Drink Condition | Interaction | |
| Blood glucose (mmol/L) | |||||||||||
| Fasted | 4.3 ± 0.1 | 4.3 ± 0.2 | 4.2 ± 0.2 | 4.5 ± 0.1 | 4.5 ± 0.1 | 4.2 ± 0.2 | 4.4 ± 0.2 | 4.5 ± 0.1 | 0.68 | 0.24 | 0.23 |
| Peak | 4.7 ± 0.1 | 4.8 ± 0.1 | 7.8 ± 0.3 | 6.3 ± 0.3 | 4.9 ± 0.1 | 4.7 ± 0.1 | 8.1 ± 0.3 | 6.9 ± 0.3 | 0.27 | <0.001 | 0.54 |
| Time to peak (min) | 50 ± 13 | 68 ± 17 | 34 ± 3 1 | 30 ± 3 | 26 ± 13 | 75 ± 17 | 51 ± 3 1 | 36 ± 3 | 0.007 | <0.001 | 0.031 |
| Return to baseline | 88 ± 26 | 41 ± 13 | 106 ± 15 | 91 ± 18 | 60 ± 22 | 125 ± 23 | 132 ± 15 | 153 ± 18 | 0.030 | 0.83 | 0.23 |
| Net iAUC0–60min | −0.1 ± 0.1 | 0.0 ± 0.1 | 2.1 ± 0.2 | 0.9 ± 0.2 | 0.1 ± 0.1 | 0.1 ± 0.1 | 2.1 ± 0.2 | 1.3 ± 0.2 | 0.29 | <0.001 | 0.48 |
| Net iAUC0–180min | −0.1 ± 0.1 | 0.0 ± 0.1 | 0.7 ± 0.2 | 0.3 ± 0.1 | −0.1 ± 0.1 | 0.1 ± 0.1 | 1.1 ± 0.2 | 0.7 ± 0.2 | 0.08 | <0.001 | 0.27 |
| Plasma insulin (mU/L) | |||||||||||
| Fasted | 5.3 ± 1.0 | 4.8 ± 0.8 | 6.9 ± 1.1 | 6.2 ± 1.0 | 4.1 ± 1.0 | 4.5 ± 0.8 | 4.1 ± 1.1 | 4.5 ± 1.0 | 0.22 | 0.41 | 0.13 |
| Peak | 11.7 ± 1.9 | 33.2 ± 6.9 2 | 55.9 ± 7.3 2 | 93.3 ± 16.8 | 9.7 ± 1.9 | 31.7 ± 6.9 | 36.5 ± 7.3 | 72.7 ± 16.9 | 0.34 | <0.001 | 0.006 |
| Time to peak (min) | 35 ± 13 | 32 ± 3 3 | 33 ± 2 3 | 36 ± 3 | 32 ± 4 | 48 ± 3 3 | 46 ± 2 3 | 42 ± 3 | 0.001 | 0.91 | 0.038 |
| Return to baseline | 73 ± 26 | 132 ± 8 | 112 ± 12 | 160 ± 11 | 109 ± 18 | 149 ± 8 | 163 ± 12 | 166 ± 11 | 0.011 | 0.068 | 0.14 |
| Net iAUC0–60min | 1.8 ± 0.5 | 16.5 ± 3.8 | 27.1 ± 4.4 | 46.2 ± 9.3 | 2.3 ± 0.5 | 15.5 ± 3.8 | 20.9 ± 4.4 | 39.8 ± 9.3 | 0.59 | <0.001 | 0.26 |
| Net iAUC0–180min | 0.2 ± 0.6 | 8.3 ± 1.9 | 10.7 ± 2.4 | 25.8 ± 6.2 | 1.5 ± 0.6 | 9.6 ± 1.9 | 11.6 ± 2.4 | 26.6 ± 6.2 | 0.77 | <0.001 | 0.99 |
| Plasma glucagon (pg/mL) | |||||||||||
| Fasted | 9.7 ± 1.4 | 10.9 ± 1.6 | 9.8 ± 1.4 | 10.3 ± 1.5 | 8.7 ± 1.4 | 9.1 ± 1.6 | 8.1 ± 1.4 | 9.6 ± 1.5 | 0.51 | 0.27 | 0.69 |
| Peak/Nadir | 11.2 ± 1.5 | 36.4 ± 5.8 | 10.7 ± 1.4 | 22.6 ± 3.1 | 10.2 ± 1.5 | 33.1 ± 5.8 | 9.1 ± 1.4 | 22.1 ± 3.1 | 0.71 | <0.001 | 0.73 |
| Time to peak (min) | 68 ± 22 | 57 ± 17 | 68 ± 24 | 54 ± 9 | 65 ± 22 | 51 ± 17 | 56 ± 24 | 48 ± 9 | 0.83 | 0.65 | 0.98 |
| Return to baseline | 54 ± 16 | 176 ± 153 | 71 ± 29 | 176 ± 51 | 126 ± 39 | 391 ± 153 | 133 ± 29 | 277 ± 51 | 0.11 | 0.011 | 0.69 |
| Net iAUC0–60min | −0.7 ± 0.0 | 16.3 ± 2.6 | −4.6 ± 0.7 | 6.3 ± 1.5 | −0.1 ± 0.0 | 13.5 ± 2.6 | −2.4 ± 0.7 | 6.3 ± 1.5 | 0.98 | <0.001 | 0.33 |
| Net iAUC0–180min | −0.9 ± 0.3 | 10.8 ± 1.3 | −3.9 ± 0.8 | 5.2 ± 1.3 | −0.5 ± 0.3 | 9.9 ± 1.3 | −3.2 ± 0.8 | 5.1 ± 1.3 | 0.95 | <0.001 | 0.92 |
Blood glucose (mmol/L), plasma insulin (mU/L) and glucagon (pg/mL) concentrations fasted (baseline), peak, time to peak (min), return to baseline (min), Net iAUC0–60min (change from baseline area under the curve during the first hour), Net iAUC0–180min (change from baseline area under the curve during the three hours) following drink ingestion containing (i) flavored water (C, control, ~2 kcal), (ii) 30 g whey protein (P), (iii) 30 g glucose (G) or (iv) 30 g whey protein + 30 g glucose (GP) in younger and older men. Effects of age and drink condition and the interaction effect were determined using a mixed-effect model using G and GP for glucose and P, G and GP for insulin and glucagon. 1 The age × drink-condition interaction, p = 0.031 (time to peak glucose is longer after G in older than younger men). 2 The age × drink-condition interaction, p = 0.006 (peak insulin concentration is higher after G than P in younger but not older men). 3 The age drink-condition interaction, p = 0.038 (time to peak insulin is longer after P and G in older than younger men). Drink-condition effects: GP vs. G reduced peak (p < 0.001) and Net iAUC (p < 0.001) glucose concentrations and the peak occurred earlier (p < 0.001) in both older and younger men: P, G, GP vs. C increased Net iAUC insulin concentrations (p < 0.001); G vs. C decreased and P, GP vs. C, P vs. GP increased Net iAUC glucagon concentrations (p < 0.001). Age effects: older vs. younger later peak (p = 0.007) and return to baseline (p = 0.030) glucose concentrations; older vs. younger later peak (p = 0.001) and return to baseline (p = 0.01) insulin concentrations.