Prevalence and incidence of thyroid dysfunction in type 1 diabetes, type 2 diabetes and latent autoimmune diabetes of adults: The Fremantle Diabetes Study Phase II.

OBJECTIVE: Since the results of published studies assessing thyroid dysfunction complicating diabetes have been variable in quality, inconsistent and may not reflect contemporary clinical care, the aim of this study was to determine its prevalence and incidence in a large, well-characterized, representative cohort. DESIGN: Community-based, longitudinal, observational study. PATIENTS: A total of 1617 participants from the Fremantle Diabetes Study Phase II (FDS2), including 130 (8.0%) with type 1 diabetes, 1408 (87.1%) with type 2 diabetes, and 79 (4.9%) with latent autoimmune diabetes of adults (LADA). MEASUREMENTS: Serum thyrotropin (TSH) and free thyroxine (FT4) at baseline between 2008 and 2011 and in those attending Year 4 follow-up. RESULTS: The prevalence of known thyroid disease (ascertained from baseline self-reported thyroid medication use or hospitalization data) was 11.7% (189/1617). Of the remaining 1428 participants, 5.1% (73/1428) had biochemical evidence of subclinical hypothyroidism, 1.1% (15/1428) overt hypothyroidism, 0.1% (2/1428) subclinical hyperthyroidism and 0.2% (3/1428) overt hyperthyroidism, representing an overall baseline prevalence of thyroid disease of 17.4% (282/1617). During 5694 patient-years of follow-up, 25 (3.0%) of the 844 with a normal baseline TSH and follow-up data developed known thyroid disease. Of the remaining 819, 3.4% developed subclinical hypothyroidism, 0.2% overt hypothyroidism and 0.5% subclinical hyperthyroidism. There were no statistically significant differences in the prevalence or incidence of thyroid dysfunction by diabetes type. CONCLUSIONS: Thyroid dysfunction, known or detected through screening, is common in diabetes. These data suggest the need for periodic clinical and biochemical screening for thyroid disease in all types of diabetes.

Higher free thyroxine levels are associated with frailty in older men: the Health In Men Study.

OBJECTIVE: Frailty is common in the elderly and predisposes to ill-health. Some symptoms of frailty overlap those of thyroid dysfunction, but it is unclear whether differences in thyroid status influence risk of frailty. We evaluated associations between thyroid status and frailty in older men. DESIGN: Cross-sectional epidemiological study. PARTICIPANTS: Community-dwelling men aged 70-89 years. MEASUREMENTS: Circulating thyrotropin (TSH) and free thyroxine (FT(4) ) were assayed. Frailty was assessed as ≥3 of the Fatigue, Resistance, Ambulation, Illnesses and Loss (FRAIL) scale's 5 domains: fatigue; resistance (difficulty climbing flight of stairs); ambulation (difficulty walking 100 m); illness (>5); or weight loss (>5%), blinded to hormone results. RESULTS: Of 3943 men, 27 had subclinical hyperthyroidism, 431 subclinical hypothyroidism and 608 were classified as being frail (15·4%). There was an inverse log-linear association of TSH with FT(4). There was no association between TSH and frailty. After adjusting for covariates, men with FT(4) in the highest two quartiles had increased odds of being frail (Q3:Q1, odds ratio [OR] = 1·32, 95% confidence interval [CI] = 1·01-1·73 and Q4:Q1, OR = 1·36, 95% CI = 1·04-1·79, P = 0·010 for trend). Higher FT(4) was associated with fatigue (P = 0·038) and weight loss (P < 0·001). The association between FT(4) and frailty remained significant when the analysis was restricted to euthyroid men. CONCLUSIONS: High-normal FT(4) level is an independent predictor of frailty among ageing men. This suggests that even within the euthyroid range, circulating thyroxine may contribute to reduced physical capability. Further studies are needed to clarify the utility of thyroid function testing and the feasibility of preventing or reversing frailty in older men.