Development of biologically-controlled insulin pumps with glucose-dependent release.

: An experimental insulin pump has been developed in which living microorganisms are used to measure glucose concentration and to produce the energy required to control the release of insulin. The insulin pump consists of a miniaturised bioreactor containing 50 mg freeze-dried yeast. 300 microL of glucose-containing liquid are injected into the bioreactor through a septum. When solutions containing 100 mg or 400 mg glucose in 100 mL are used, the amounts of insulin released differ significantly even within the first measuring interval of 15 min (t-test, p < 0.05). Within 120 min, 4 I.U. and 17 I.U. insulin respectively are released from the two glucose solutions.