QUICKI does not accurately reflect changes in insulin sensitivity with exercise training

Area of Science:

• Metabolic Health
• Exercise Physiology
• Biostatistics

Background:

• Insulin resistance is a key factor in metabolic dysfunction.
• Exercise training is a known intervention to improve insulin sensitivity.
• Accurate and simple indices for assessing insulin sensitivity are crucial for clinical and research applications.

Purpose of the Study:

• To evaluate the validity of the quick insulin sensitivity check index (QUICKI) in reflecting exercise-induced changes in insulin sensitivity.
• To compare the QUICKI with a gold-standard method (minimal model) for estimating insulin sensitivity.
• To determine if fasting insulin alone is as effective as QUICKI in assessing insulin sensitivity.

Main Methods:

• Sedentary, non-diabetic adults participated in a 6-month exercise training program.
• Insulin sensitivity was measured using a frequently sampled intravenous glucose tolerance test and analyzed with Bergman's minimal model.
• QUICKI was calculated using fasting insulin and glucose levels before and after the training intervention.

Main Results:

• Exercise training significantly improved insulin sensitivity as assessed by the minimal model (P = 0.003).
• QUICKI did not show a significant change after exercise training (P = 0.12).
• While QUICKI and fasting insulin correlated with the minimal model at baseline and post-training, they did not correlate with the *changes* in insulin sensitivity induced by exercise.

Conclusions:

• Fasting insulin is a viable alternative to QUICKI for assessing basal insulin sensitivity in non-diabetic individuals.
• QUICKI is not a reliable indicator of exercise-induced improvements in insulin sensitivity at the individual level.
• Further research is needed to develop sensitive indices that capture dynamic changes in insulin sensitivity.