Originals

Diabetologia

, Volume 32, Issue 3, pp 213-217

First online:

In vivo molecular sensing in diabetes mellitus: an implantable glucose sensor with direct electron transfer

  • J. C. PickupAffiliated withDivision of Chemical Pathology, United Medical and Dental Schools of Guy's and St Thomas's Hospitals, Guy's Hospital
  • , G. W. ShawAffiliated withDivision of Chemical Pathology, United Medical and Dental Schools of Guy's and St Thomas's Hospitals, Guy's Hospital
  • , D. J. ClaremontAffiliated withDivision of Chemical Pathology, United Medical and Dental Schools of Guy's and St Thomas's Hospitals, Guy's Hospital

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Summary

Miniature, amperometric glucose sensors were constructed for implantation in the subcutaneous tissue of normal and insulin-dependent diabetic subjects. To minimise dependence on fluctuating tissue oxygen tension, we employed the technology of mediated electron transfer, with 1,1′-dimethylferrocene acting as the redox shuttle between immobilized glucose oxidase and a platinum base electrode. In 6 normal subjects, the subcutaneous sensor responses mirrored the simultaneously-measured changes in blood glucose concentration after a 75 g oral glucose load and after intravenous injection of 0.15 U/kg short-acting insulin, though increases and decreases in the sensor output were slower than the glycaemic changes. The mean peak delay in sensor response after the oral glucose was 40 min (range 0–45 min) and the delay in the hypoglycaemic nadir was 4 min (range 0–15 min). In 5 insulin-dependent diabetic subjects, spontaneous and induced hypoglycaemia was detectable by the implanted sensor. In addition, marked and frequent oscillations in the sensor current occurred in several normal and diabetic individuals as the blood glucose fell below about 1.9 mmol/l. These oscillations were present in a diabetic subject who had lost adrenergic warning symptoms to hypoglycaemia. Continuous metabolic monitoring in diabetes, particularly the detection of hypoglycaemia, may be possible with implanted sensors based on this technology.

Key words

Glucose sensor enzyme electrode biosensor glucose oxidase ferrocene diabetes mellitus