Two hundred and seventy-three patients with thalassaemia major (TM) were followed in the Ferrara Thalassaemia Centre over a thirty-year period. Forty-two patients had
insulin dependent diabetes mellitus (
IDDM). The first case was diagnosed in 1973. The incidence of
IDDM peaked in 1986 (3.9%), and it was 0.7% at the time of the study (March 1998). The prevalence of
IDDM increased progressively over time, reaching 14.2% in 1998. Mean age at diagnosis of
IDDM was 18.2 -/+ 3.6 years and this also rose significantly during the study period (p<0.01).
Hypogonadism was present in 91% of patients with
IDDM,
hypothyroidism in 68%,
hypoparathyroidism in 21%, and cardiopathy in 69%, all significantly more prevalent than in patients without
IDDM. These complications appeared with the same frequency before and after the diagnosis of
IDDM. Survival of patients with and without
IDDM was similar and no difference in the primary cause of death was found between the two groups. Main risk factors associated with
IDDM were poor compliance with desferioxamine (DFO) treatment (p<0.05%), advanced age at the start of intensive
chelation therapy (p<0.001),
liver cirrhosis or severe
fibrosis (p<0.0001, odds ratio 9.5, CI 95% 2.8-32.6). Prevalence of
impaired glucose tolerance (IGT) was highest in 1981, 1984, and 1985 when the incidence of
IDDM was increasing; in 1995 the prevalence of IGT in patients aged 16-20 years was lower in comparison with that observed in 1975 (17% vs. 59%, p<0.01). Risk factors associated with IGT were: male sex (p<0.05), poor compliance with DFO
therapy (p<0.05) and liver
iron concentration 4 times above the normal value. In conclusion, our longitudinal study confirms that the incidence of
IDDM and prevalence of IGT have been decreasing over the course of the last decade, appearing at a more advanced age, although some differences have not reached statistical significance.
Iron overload and
liver disease were the main associated risk factors, while positive family history for diabetes did not influence
glucose metabolism in our patients.