This abstract is the one I was ref to.
Now they didn't measure insulin, so we don't know if that is part of the mechanism and creatine doesn't alter substrate utilization during exercise, do don't panic if you take it before cardio. Lastly, how much of an impact this really has is unclear and it was done in guys. Same effect in women, we don't know and I'd like to see this replicated with mechanisms and also in women.
Huso, M. Erik, Jeffrey S Hampl, Carol S. Johnston,
and Pamela D. Swan.
Creatine supplementation influences substrate utilization at rest.
J Appl Physiol 93: 2018–2022, 2002.
The influence of creatine supplementation
on substrate utilization during rest was investigated
using a double-blind crossover design. Ten active men
participated in 12 wk of weight training and were given
creatine and placebo (20 g/day for 4 days, then 2 g/day for 17
days) in two trials separated by a 4-wk washout. Body composition, substrate utilization, and strength were assessed
after weeks 2, 5, 9, and 12. Maximal isometric contraction [1
repetition maximum (RM)] leg press increased significantly
(P< 0.05) after both treatments, but 1-RM bench press was
increased (33 +/- 8 kg, P< 0.05) only after creatine. Total body
mass increased (1.6 +/- 0.5 kg, P< 0.05) after creatine but not
after placebo. Significant (P < 0.05) increases in fat-free
mass were found after creatine and placebo supplementation
(1.9 +/- 0.8 and 2.2 +/- 0.7 kg, respectively). Fat mass did not
change significantly with creatine but decreased after the
placebo trial (2.4 +/- 0.8 kg, P < 0.05). Carbohydrate oxidation
was increased by creatine (8.9 +/- 4.0%, P < 0.05),
whereas there was a trend for increased respiratory exchange
ratio after creatine supplementation (0.03 +/- 0.01,
P < 0.07). Changes in substrate oxidation may influence the
inhibition of fat mass loss associated with creatine after
weight training.