Our aim was to determine the incidence of type 2 diabetes mellitus in a nation-wide population based cohort from Spain (di@bet.es study). The target was the Spanish population. In total 5072 people older than 18 years,were randomly selected from all over Spain). Socio-demographic and clinical data, survey on habits (physical activity and food consumption) and weight, height, waist, hip and blood pressure were recorder. A fasting blood draw and an oral glucose tolerance test were performed. Determinations of serum glucose were made. In the follow-up the same variables were collected and HbA1c was determined. A total of 2408 subjects participated in the follow-up. In total, 154 people developed diabetes (6.4% cumulative incidence in 7.5 years of follow-up). The incidence of diabetes adjusted for the structure of age and sex of the Spanish population was 11.6 cases/1000 person-years (IC95% = 11.1–12.1). The incidence of known diabetes was 3.7 cases/1000 person-years (IC95% = 2.8–4.6). The main risk factors for developing diabetes were the presence of prediabetes in cross-sectional study, age, male sex, obesity, central obesity, increase in weight, and family history of diabetes. This work provides data about population-based incidence rates of diabetes and associated risk factors in a nation-wide cohort of Spanish population.

Background: The aim of this study was to investigate the national prevalence of thyroid dysfunction in Spain and its association with various clinical, environmental, and demographic variables. Methods: The study included 4554 subjects (42.4% men) with a mean age of 50 years (range 18–93 years), who were participants in a national, cross-sectional, population-based survey conducted in 2009–2010. Data gathered included clinical and demographic characteristics, physical examination, and blood sampling. Thyrotropin, free thyroxine, free triiodothyronine, and thyroid peroxidase antibody (TPOAb) concentrations were analyzed by electrochemiluminescence. Urinary iodine (UI) levels were measured in an isolated urine sample. Results: The prevalence of treated hypothyroidism, untreated subclinical hypothyroidism, and untreated clinical hypothyroidism was 4.2% [confidence interval (CI) 3.6–4.9%], 4.6% [CI 4.0–5.2%], and 0.3% [CI 0.1–0.5%], respectively. The prevalence of total hypothyroidism (including all fractions) was 9.1% [CI 8.2–10.0%]. The prevalence of total hyperthyroidism was 0.8% [CI 0.6–1.1]. A total of 7.5% [CI 6.7–8.3%] of the population tested positive for TPOAbs (≥50 IU/mL). In multivariate logistic regression models, TPOAbs were strongly associated with both hypothyroidism ( p < 0.001) and hyperthyroidism ( p = 0.005), whereas high UI levels (>200 μg/g creatinine) were associated with hypothyroidism ( p < 0.001). The positive association between UI and hypothyroidism remained for both treated ( p < 0.001) and untreated ( p < 0.05) hypothyroidism, whereas it was especially significant for non-autoimmune (TPOAbs negative) forms ( p < 0.001). At UI levels ≥200 μg/g, there was a positive correlation between UI and thyrotropin levels (β = 0.152, p < 0.001) and a negative correlation between UI and free triiodothyronine levels (β = −0.134, p = 0.001). Conclusion: According to the data, a large proportion (10%) of the Spanish population has some evidence of thyroid dysfunction. High TPOAb concentrations were associated with both hypo- and hyperthyroidism, whereas high UI concentrations were associated with hypothyroidism.

Objective: To analyze the reference range of thyroid‐stimulating hormone (TSH) in different BMI categories and its impact on the classification of hypothyroidism.Methods: The study included 3,928 individuals free of thyroid disease (without previous thyroid disease, no interfering medications, TSH <10 µUI/mL and thyroid peroxidase antibodies [TPO Abs] <50 IU/mL) who participated in a national, cross‐sectional, population‐based study and were representative of the adult population of Spain. Data gathered included clinical and demographic characteristics, physical examination, and blood and urine sampling. TSH, free thyroxine, free triiodothyronine, and TPO Ab were analyzed by electrochemiluminescence (E170, Roche Diagnostics, Basel, Switzerland).Results: The reference range (p2.5‐97.5) for TSH was estimated as 0.6 to 4.8 µUI/mL in the underweight category (BMI<20 kg/m²), 0.6 to 5.5 µUI/mL in the normal‐weight category (BMI 20‐24.9 kg/m²), 0.6 to 5.5 µUI/mL in the overweight category (BMI 25‐29.9 kg/m²), 0.5 to 5.9 µUI/mL in the obesity category (BMI 30‐39.9 kg/m²), and 0.7 to 7.5 µUI/mL in the morbid obesity category (BMI ≥40). By using the reference criteria for the normal‐weight population, the prevalence of high TSH levels increased threefold in the morbid obesity category (P < 0.01).Conclusions: Persons with morbid obesity might be inappropriately classified if the standard ranges of normality of TSH for the normal‐weight population are applied to them.

Objective: The activity of brown adipose tissue is sensitive to changes in ambient temperature. A lower exposure to cold could result in an increased risk of developing diabetes at population level, although this factor has not yet been sufficiently studied. Design: We studied 5072 subjects, participants in a national, cross-sectional population-based study representative of the Spanish adult population (Di@bet.es study). All subjects underwent a clinical, demographic and lifestyle survey, a physical examination and blood sampling (75 g oral glucose tolerance test). Insulin resistance was estimated with the homeostasis model assessment (HOMA-IR). The mean annual temperature (°C) in each individual municipality was collected from the Spanish National Meteorology Agency. Results: Linear regression analysis showed a significant positive association between mean annual temperature and fasting plasma glucose (β: 0.087, P < 0.001), 2 h plasma glucose (β: 0.049, P = 0.008) and HOMA-IR (β: 0.046, P = 0.008) in multivariate adjusted models. Logistic regression analyses controlled by multiple socio-demographic variables, lifestyle, adiposity (BMI) and geographical elevation showed increasing odds ratios for prediabetes (WHO 1999), ORs 1, 1.26 (0.95–1.66), 1.08 (0.81–1.44) and 1.37 (1.01–1.85) P for trend = 0.086, diabetes (WHO 1999) ORs 1, 1.05 (0.79–1.39), 1.20 (0.91–1.59) and 1.39 (1.02–1.90) P = 0.037, and insulin resistance (HOMA-IR ≥75th percentile of the non-diabetic population): ORs 1, 1.03 (0.82–1.30), 1.22 (0.96–1.55), 1.26 (0.98–1.63) (P for trend = 0.046) as the mean annual temperature (into quartiles) rose. Conclusions: Our study reports an association between ambient temperature and the prevalence of dysglycemia and insulin resistance in Spanish adults, consistent with the hypothesis that a lower exposure to cold could be associated with a higher risk of metabolic derangements.

Previous studies have suggested that iron deficiency (ID) may impair thyroid hormone metabolism, however replication in wide samples of the general adult population has not been performed. We studied 3846 individuals free of thyroid disease, participants in a national, cross sectional, population based study representative of the Spanish adult population. Thyroid stimulating hormone (TSH), free thyroxin (FT4) and free triiodothyronine (FT3) were analyzed by electrochemiluminescence (E170, Roche Diagnostics). Serum ferritin was analyzed by immunochemiluminescence (Architect I2000, Abbott Laboratories). As ferritin levels decreased (>100, 30–100, 15–30, <15 µg/L) the adjusted mean concentrations of FT4 (p < 0.001) and FT3 (p < 0.001) descended, whereas TSH levels remained unchanged (p = 0.451). In multivariate logistic regression models adjusted for age, sex, UI, BMI and smoking status, subjects with ferritin levels <30 µg/L were more likely to present hypothyroxinemia (FT4 < 12.0 pmol/L p5): OR 1.5 [1.1–2.2] p = 0.024, and hypotriiodothyroninemia (FT3 < 3.9 pmol/L p5): OR 1.8 [1.3–2.6] p = 0.001 than the reference category with ferritin ≥30 µg/L. There was no significant heterogeneity of the results between men, pre-menopausal and post-menopausal women or according to the iodine nutrition status. Our results confirm an association between ID and hypothyroxinemia and hypotriiodothyroninemia in the general adult population without changes in TSH.