Effect of weight loss on the pulsatile insulin secretion

The aim of the study was to assess whether pulsatile insulin secretion is variable in the same individual and is related to changes in insulin sensitivity. Insulin sensitivity and pulsatility were measured before and after weight reduction in nine obese subjects. A pulsatility analysis was done using the PulsDetekt program. Blood was sampled every 2 min over a period of 90 min. The secretion randomness was quantified using approximate entropy (ApEn), and ApEn normalized by SD of the insulin time series (nApEn). Lower values indicate more regular secretion. Insulin sensitivity was measured using the homeostasis model assessment. Data are presented as median, minimum-maximum. After weight loss insulin sensitivity was increased (12.16, 7.60-76.70 vs. 38.96, 19.88-74.96%), the number of insulin pulses was reduced (11, 8-16 vs. 9,6-12), and they were more regular (ApEn, 0.92, 0.53-133 vs. 0.69,0,40-1.27; nApEn, 1.07, 0.74-1.33 vs. 0.97, 0.54-1.42). Before and after the weight loss there was a correlation between ApEn and nApEn and insulin sensitivity. Therefore, insulin secretion regularity is variable in the same individual and is related to insulin sensitivity.