Can a fasting blood marker estimate insulin sensitivity as well as other simple indices?

Details

Insulin resistance is associated with an increased risk of cardiovascular disease and diabetes. It can be assessed using complex reference techniques, such as a clamp or the frequently sampled intravenous glucose tolerance test (FSIVGTT). Simple indices derived from fasting insulin and glucose concentrations have therefore been proposed. This study assessed fasting serum insulin-like growth factor binding protein-1 (IGFBP-1) as a simple index of insulin sensitivity, comparing it with other simple indices and FSIVGTT.

In a comparative correlation study, researchers examined correlations with FSIVGTT-derived insulin sensitivity (Si) in 22 subjects with normal glucose tolerance (NGT) and nine with impaired fasting glucose (IFG). The measures tested were fasting serum IGFBP-1, fasting plasma insulin (FPI), homeostasis model assessment (HOMA-IR), quantitative insulin check index (QUICKI), fasting glucose to insulin ratio (FGIR), Raynaud, and insulin glycaemic index (ISI-gly).

In the NGT group, IGFBP-1 correlated more strongly with Si than any other index, both before natural logarithm (ln) transformation (r = 0.76) and after transformation (r = 0.79). In the IFG group, IGFBP-1 was described as weakly correlated with Si before and after ln-transformation (r = 0.55 and r = 0.56, respectively). ISI-gly had the strongest correlation with Si in that group: r = 0.77 before transformation and r = 0.85 after transformation.

The authors concluded that fasting serum IGFBP-1 could be used as a simple, reliable marker of insulin sensitivity in subjects with NGT. For more accurate estimation of insulin sensitivity in subjects with normal glucose tolerance and those with IFG, they preferred ln-transformed values over raw data.