2.2.3. Biochemical Assays
Insulin sensitivity was measured by the short insulin tolerance test (SITT) using the slope of blood
glucose concentration from 3 to 15 min after a low dose intravenous bolus of rapid insulin. In
particular, 0.1 IU/kg of rapid insulin was injected intravenously after the fasting blood glucose had
been measured. Glycemia was then recorded every 3 min for a total duration of 15 min using the
HEMOCUE 201+ glucose analyzer (Angelholm, Sweden). The faster the decline in glucose
concentration, the more insulin-sensitive the subject is. The slope of the linear decline in plasma
glucose, which is the insulin sensitivity index (KITT) was calculated by dividing ln 2 (0.693) by the
plasma glucose half-life (50% from baseline) [25].
KITT = (0.693/t1/2) × 100
where t1/2 represents the half-life of the decrease in plasma glucose. Given that this test is population
dependent and that insulin sensitivity has a normal distribution, we defined as insulin-resistant, all
subjects with insulin sensitivity index (KITT) within the first tertile of the insulin sensitivitydistribution of the study population. Subjects with KITT in the last tertile of the insulin sensitivity
distribution were considered as insulin-sensitive while all those with KITT in the middle tertile were
considered as having intermediate insulin sensitivity.
Five (5) mL of whole blood was collected from a peripheral vein for lipid assay. The blood was
centrifuged at 4000 rev/min at 4 °C and the serum obtained was stored at −20 °C until analysis. Total
cholesterol (TC) and triglycerides (TG) were measured by the LISA 380 Plus automat (Hycel
Diagnostics, France). All these measurements were repeated eight weeks after onset of intervention