Idiopathic haemochromatosis and diabetes mellitus

The separate influences of familial factors and of iron overload on the occurrence of diabetes in idiopathic haemochromatosis (I.H.) have been re‐examined by means of a genetical analysis.The prevalence of overt diabetes was measured in the parents of 96 patients suffering from I.H., either associated (H.D.) or not (H.D.) with diabets mellitus (D). Twelve out of 132 parents of H.D. patients had diabetes without iron overload, a percentage similar to that reported for the parents of patients with maturity onset diabetcs without haemochromatosis. For (H.D.) patients the prevalence of parental diabetes was nil and very close to that encountered for the same age group in the general population. The difference between the prevalence rates in the two groups was significant (P < 0.05).The magnitude of the iron was found to be similar in the two groups. The age at diagnosis did not differ. This suggests that iron overload (i.o.) is not the only causal factor in diabetes occurring in I.H.It was therefore concluded that diabetes mellitus in haemochromatotic patients is genetically determined per se, and that iron overload, through siderosclerotic damage of the pancreas, permits the recogn