Should thyroid-stimulating hormone goals be reviewed in patients with type 1 diabetes mellitus? Results from the Brazilian Type 1 Diabetes Study Group

AIMS

To investigate if thyroid-stimulating hormone (TSH) levels are associated with any differences in glycaemic control or diabetes-related complications in individuals with Type 1 diabetes.

METHODS

This observational, cross-sectional and multicentre study included patients with Type 1 diabetes for ≥ 5 years, with a recent TSH measurement and without a known previous thyroid disease. Patients were divided into three groups according to TSH levels: 0.4-2.5 mU/l; 2.5-4.4 mU/l; and ≥ 4.5 mU/l.

RESULTS

We included 1205 individuals with a mean ± sd age of 23.8 ± 11.3 years. Seven patients had TSH levels <0.4 mU/l and were excluded from the comparison between groups. HbA1c levels, systolic and diastolic blood pressure, LDL cholesterol and disease duration were similar in all groups (P = 0.893, P = 0.548, P = 0.461, P = 0.575 and P = 0.764, respectively). The rates of diabetic retinopathy and GFR < 60/mL/min/1.73 m(2) differed between groups (P = 0.006 and P < 0.001, respectively) and were lower in those with lower TSH levels. Multivariate analysis confirmed these associations. The frequencies of retinopathy and GFR < 60 mL/min/1.73 m(2) were higher not only in patients with TSH ≥ 4.5 mU/l (odds ratio 1.878 and 2.271, respectively) but also in those with TSH levels of 2.5-4.4 mU/l (odds ratio 1.493 and 2.286, respectively), when compared with patients with TSH levels of 0.4-2.5 mU/l.

CONCLUSIONS

TSH levels of 0.4-2.5 mU/l are associated with a lower risk of diabetic retinopathy and renal failure in individuals with Type 1 diabetes, independently of glycaemic control and duration of the disease.

Prevalence, awareness, and treatment of hypertension in patients with type 1 diabetes: a nationwide multicenter study in Brazil

Objective. This study evaluated the prevalence, awareness, and type of treatment for hypertension in Brazil in patients with type 1 diabetes (T1D). Methods. This was a cross-sectional, multicenter study that was conducted from December 2008 to December 2010 in 28 public clinics located in 20 Brazilian cities. Results. A total of 3,591 patients were studied, 56% female, average age 21.2 ± 11.7 years, with a median duration of diabetes 9.6 ± 8.1 years. Blood pressure levels were available for a total of 3,323 patients and 689 (19.2%) patients were hypertensive. Hypertensive patients were older, exhibited longer duration of diabetes, and had higher body mass index (BMI), total cholesterol, triglycerides, and LDL-C values (P < 0.001, for all comparisons), but only 370 (53.7%) received treatment. Patient awareness of hypertension was documented in 453 (65.5%) patients. However, only 76 (22.9%) of the treated patients attained the target systolic (sBP) and diastolic blood pressures (dBP). Conclusions. Our results demonstrate that a large number of T1D patients with hypertension do not receive appropriate treatment; few of the treated T1D patients achieved the target sBP and dBP values. Greater attention should be paid to blood pressure evaluation, hypertension diagnosis, and treatment of T1D patients in Brazil.

Impact of diabetes on cardiovascular disease: an update

Cardiovascular diseases are the most prevalent cause of morbidity and mortality among patients with type 1 or type 2 diabetes. The proposed mechanisms that can link accelerated atherosclerosis and increased cardiovascular risk in this population are poorly understood. It has been suggested that an association between hyperglycemia and intracellular metabolic changes can result in oxidative stress, low-grade inflammation, and endothelial dysfunction. Recently, epigenetic factors by different types of reactions are known to be responsible for the interaction between genes and environment and for this reason can also account for the association between diabetes and cardiovascular disease. The impact of clinical factors that may coexist with diabetes such as obesity, dyslipidemia, and hypertension are also discussed. Furthermore, evidence that justify screening for subclinical atherosclerosis in asymptomatic patients is controversial and is also matter of this review. The purpose of this paper is to describe the association between poor glycemic control, oxidative stress, markers of insulin resistance, and of low-grade inflammation that have been suggested as putative factors linking diabetes and cardiovascular disease.