1. The aim of the study was to examine the responses of plasma glucose, C-peptide immunoreactivity (CPR) and total immunoreactive insulin (IRI) to a standard meal in heroin addicts, since the presence of immunoreactive β-endorphin has been demonstrated in human endocrine pancreas.
2. Ten heroin addicts and 10 control subjects participated in the study. The addicts had been taking heroin (from 0.5 to 2 g/day) for at least 2 months and they had no detectable diseases.
3. After a 12 h fast, each subject received a standard meal; blood samples were taken at − 15, 0, 15, 30, 60 and 120 min to determine glucose, CPR and IRI. Calculation of the CPR/IRI molar ratio was used as a semiquantitative estimation of the hepatic extraction of insulin.
4. No difference in plasma glucose was observed between the groups. Addicts had lower CPR than normals at 15, 30 and 120 min (P < 0.01). On the contrary, IRI was higher in addicts than in normals (P < 0.05 at − 15 and 0 min, P < 0.01 at 15, 30 and 60 min), except at 120 min. The CPR/IRI molar ratio was lower in addicts (P < 0.01).
5. Heroin addiction seems to produce a β-cell failure and contemporaneously a state of hyperinsulinaemia; blood glucose remains in the normal range.
6. We conclude that chronic heroin addiction may produce a change in the rate of hepatic extraction of insulin.
