N. Stefan et al., Effect of the pattern of elevated free fatty acids on insulin sensitivity and insulin secretion in healthy humans, HORMONE MET, 33(7), 2001, pp. 432-438
In order to investigate whether the pattern of elevated free fatty acids (F
FAs) has any effect on insulin sensitivity and insulin secretion in humans,
we produced 2 distinct serum FFA patterns (PT 1 and 2) by infusing 6 healt
hy volunteers with 2 different lipid emulsions plus heparin for 24 hours. A
hyperglycemic clamp (approx. 8 mM, 140 min) was performed before and 5 and
24 hours after both lipid infusions to determine insulin sensitivity and i
nsulin secretion simultaneously. Total FFAs had increased comparably by 24
hours (2020 +/- 268 muM in PT 1) and (1812 +/- 154 LM in PT 2, p = 0.24). S
erum PT 1 contained 66 % saturated FFAs plus monoenes and 34% polyenes, whi
le PT 2 contained 80% saturated FFAs plus monoenes and 20% polyenes. Thus,
the ratio of polyunsaturated to saturated plus monoenes was about 0.5 in PT
1 vs. 0.25 in PT 2. In PT 1, the insulin sensitivity index (ISI) decreased
by 20 +/- 7% and 27 +/- 10% from basal after 5 and 24 hours, respectively.
In PT 2, the ISI decreased significantly more after 5 (41 +/- 7 %, p = 0.0
08) and 24 hours (52 +/- 6 %, p = 0.005). In contrast, different phases of
insulin secretion did not change during the lipid infusion and did not vary
between the two FFA profiles. In conclusion, these findings provide prelim
inary evidence that the composition of elevated serum FFAs; influenced insu
lin sensitivity in humans. The FFA pattern low in polyunsaturated FFAs redu
ced insulin sensitivity more than the pattern high in polyunsaturated FFAs.
In contrast, no effect on insulin secretion was observed.