Fig. 1
From: Assessment of CYP1A2 enzyme activity in relation to type-2 diabetes and habitual caffeine intake
Relationship between sampling time and salivary paraxanthine/caffeine ratio. Solid line: mean observed ratio estimates based on data of Spigset et al. [14]. Error bars show standard deviation across the mean of observed ratio data (n = 12). Dotted line: ratio based on fitted curve (dotted line) using a second-order polynomial model: Y = A + (B x X) + (C x X 2 ). Best-fit values (95 % confidence intervals): A = 0.016 (-0.206 - 0.238); B = 0.141 (0.090 - 0.191); C = -0.004 (-0.006 - -0.002). Equation: Y = 0.016 + (0.141 x X) + (-0.004 x X 2 ); Y = paraxanthine/caffeine ratio; X = time interval between final caffeine intake and saliva sampling