Insulin serum concentrations might not reflect actual concentration of insulins at the tissue level. Insulins designed to act in the liver benefit from the direct measurement of absolute insulin tissue concentrations to assess the expected PK and dynamic concentration profiles for several days on tissue level.
In a euglycaemic glucose clamp study aOFM was used to sample ISF from adipose tissue. Insulin concentrations were continuously measured for 36 h in 24 type 1 diabetes patients and absolute concentrations were determined via a no-net-flux approach.
aOFM was successfully used to measure insulin concentrations and to obtain time-resolved profiles in a clinical trial.
The ISF-to-serum concentration ratios for the new tested insulin were only half relative to human insulin. Absolute concentration and dynamic concentration profiles in serum were significantly different from adipose tissue.
Tiffner K, Boulgaropoulos B, Höfferer C, Birngruber T, Porksen N, Linnebjerg H, et al. Quantification of Basal Insulin Peglispro and Human Insulin in Adipose Tissue Interstitial Fluid by Open-Flow Microperfusion. Diabetes Technol Ther 2017;19:305–14. doi:10.1089/dia.2016.0384.