<qa>  What is the gold standard investigation of beta cell function and peripheral insulin sensitivity?One gold standard investigation of both beta cell function and peripheral insulin sensitivity is the insulin-modified frequently sampled intravenous glucose tolerance test FSIGT. The FSIGT consists in giving intravenously a glucose bolus at time point 0 followed by an intravenous administration of insulin at time point 20 minutes 18,19, 20. The determination of glucose, insulin and C-peptide at frequent intervals till time point 180 minutes allows the calculation of the acute insulin response, glucose effectiveness, insulin clearance and insulin sensitivity through the minimal model analysis 13 The intravenous administration of 3 pmolkgmin BNP achieves a plateau of increased BNP plasma concentrations after 60 minutes. In previous publications, this infusion was administered during 4 hours, achieving a steady state plasma BNP between time points 60 minutes and 240 minutes 17. Using this already established protocol, we aim to maintain constantly high plasma BNP levels throughout the three hours of the FSIGT. The combination of both BNP 17 and FSIGT 13 protocols in an interventional study will be an adequate means of investigating the impact of BNP on glucose metabolism in healthy subjects. 