Page 74 - Human Bile Acid Metabolism: a Postprandial Perspective

Chapter 4
Calculations and statistical analysis
HOMA-IR was calculated from fasting plasma glucose (FPG) and fasting plasma insulin (FPI) as described by Wallace and Matthews [21]. Fractions of a particular BA species were calculated as the sum of individual measurements of nonconjugated and glycine- and taurine-conjugated forms. Total BA were calculated by adding up all individual BA measurements. Area-under-the-curve (AUC) and incremental AUC (iAUC) were calculated using the trapezoidal method. Statistical analysis was performed using IBM SPSS Statistics 22 (IBM, Armonk, NY, USA). Data was visually and statistically assessed for normality and logarithmically transformed were appropriate. Comparisons between 2 test conditions were made using either paired t-testing for normally distributed data or Wilcoxon matched-pairs signed rank testing for nonparametric data. Correlations were assessed using Pearson’s correlation for normally distributed populations or Spearman’s Rho for nonparametric data. Data presented are mean and standard deviation (m ± s) for normally distributed variables or median and interquartile range (m [IQR]) for other variables. Graphs were made using GraphPad Prism 6.0 (GraphPad Software Inc., La Jolla, CA, USA).
Results
Baseline
We included 12 obese, insulin resistant subjects. Subject characteristics and clinical chemistry pre- and post-VLCD are summarized in Table 1.
Table 1: Study participants.
N
Sex (f/m)
Age (y)
Body weight (kg) BMI (kg/m2)
FPG (mmol/L)
FPI (pmol/L) HOMA-IR
HbA1c (mmol/mol)
Pre-VLCD 12
4/8
43.5 ± 14.2 126 ± 7 39.8 ± 2.0 4.5 ± 0.2 119 ± 11 3.5 ± 0.4 39 ± 1
Post-VLCD p
12 -
- -
- -
121 ± 7 0.0001 38.4 ± 2.0 0.0001 4.7 ± 0.1 0.78 122 ± 18 0.93 3.7 ± 0.5 0.67
- -
Values are presented as m ± SE.
72