Declining prevalence of diabetes mellitus in hereditary haemochromatosis--the result of earlier diagnosis.

AIMS: The aims of this study were to describe the prevalence and clinical features of diabetes in hereditary haemochromatosis (HH), with particular emphasis to how this has changed since the introduction of genetic testing in 1996.

SUBJECTS AND METHODS: Two hundred and thirty-seven patients were diagnosed with HH (based on elevated iron indices and liver biopsy or genetic testing) by a single physician, and all biochemical and clinical data recorded from diagnosis to the end of the study.

RESULTS: The prevalence of diabetes (21.9%) was lower than most previously published studies. There was a significantly greater prevalence of diabetes and cirrhosis in those diagnosed before the introduction of genetic testing, p<0.001. The type of genetic mutation for HH, degree of ferritin elevation at diagnosis, or the presence of cirrhosis was not predictive for the development of diabetes. Iron depletion did not result in an improvement in glycaemic control or reduction in insulin requirements in the majority of patients.

CONCLUSIONS: This is one of the largest published series of diabetes in HH. Because the occurrence of diabetes in patients with HH reduces life expectancy, our finding of a lower prevalence of diabetes is expected to translate into a greater survival rate in these patients.