Prevalence of subclinical thyroid failure in insulin-dependent diabetes.

A study was made of the distribution of primary thyroid failure, indicated by a raised serum TSH concentration, in 605 (294 males and 311females) insulin-dependent (type I) diabetics,aged 21–84 yr, not previously suspected of having thyroid disease. The prevalence of a raised serum TSHconcentration in females of all ages (17%) was significantly greater(P <0.0005) than that in males (6.1%) and increased with increasing age at onset of diabetes (P< 0.05) and age at time of study(P < 0.001) in females but not in males. There was no significant difference in the duration of diabetes when comparing patients with normal and raised serum TSH concentrations. The prevalence of a raised TSH concentration in late-onset insulin-dependent diabetics was no greater in patients requiring insulin within 3 months of diagnosis of diabetes than in those exhibiting secondary sulfonylurea failure, who required insulin more than 3 months after diagnosis. In type I diabetes, the prevalence of subclinical primary thyroid failure ...