Although several studies have been conducted to determine the effects of various components of coffee on insulin resistance in skeletal muscle, only two studies used whole coffee as the treatment [15] and [20]. Both studies concluded that coffee consumption improves insulin sensitivity in skeletal muscle by altering the insulin signaling pathway. First, it was shown that 4 weeks of caffeinated coffee consumption in the drinking water of diabetic KK-Ay mice, heterozygous for the yellow spontaneous mutation (Ay), decreased blood glucose levels after insulin stimulation and increased Akt phosphorylation in skeletal muscle compared to that in control mice drinking plain water [20]. Interestingly, although coffee consumption did alter downstream insulin signaling in response to insulin stimulation, it did not alter tyrosine phosphorylation of the insulin receptor.