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Cardio Diabetes Medicine 2017 145

Close monitoring of thyroid function particularly in Hyperthyroidism leads to hyperglycaemia affecting
patients with type 1 diabetes has long been advocat- carbohydrate metabolism through multiple mecha-
ed. An initial TSH 0and ATPO antibody testing will nisms.
help to predict the development of hypothyroidism Hyperthyroidism and Hypothyroidism may compli-
in patients with type 1 diabetes. The British Thyroid cate or exacerbate pre-existing heart disease.
Association supports ATPO testing at baseline and
TSH monitoring at yearly intervals in type 1 diabetes. Early intervention of sub-clinical hypothyroidism and
Guidelines remain unclear on testing for thyroid dys- sub-clinical hyperthyroidism may prevent heart dis-
function in newly diagnosed type 2 diabetes. There ease in individuals less than 65 years.
are large variations in the different guidelines, rang-
ing from ignoring thyroid function to yearly testing. References
Various studies have been undertaken to understand 1. Wu P. Thyroid disorders and diabetes. It is common for a person to be
the role, importance, and need of determination of affected by both thyroid disease and diabetes. Diabetes self-management.
thyroid dysfunction in the patients with type 2 diabe- 2007 Sep-Oct;24(5):80-2, 5-7.
tes[8]. Regular screening for thyroid abnormalities in 2. Vanderpump MP, Tunbridge WM, French JM, Appleton D, Bates D, Clark
all diabetic patients may allow early treatment of sub- F, et al. The incidence of thyroid disorders in the community: a twen-
clinical thyroid dysfunction. It has also been proposed ty-year follow-up of the Whickham Survey. Clinical endocrinology. 1995
Jul;43(1):55-68.
that in type 2 diabetic patients, a TSH test should be
performed at diagnosis and then repeated at least 3. Perros P, McCrimmon RJ, Shaw G, Frier BM. Frequency of thyroid dysfunc-
every 5 years. A sensitive serum TSH assay is the tion in diabetic patients: value of annual screening. Diabet Med. 1995
Jul;12(7):622-7.
screening test of choice and treatment interference
needs to be taken into account. Some guidelines 4. Duntas LH, Orgiazzi J, Brabant G. The interface between thyroid and
diabetes mellitus. Clinical endocrinology. Jul;75(1):1-9.
suggest thyroid function testing only when there is
a clinical suspicion of autoimmune disease.Recent 5. Rhee CM, Curhan GC, Alexander EK, Bhan I, Brunelli SM. Subclinical hy-
recommendations suggest more frequent testing, pothyroidism and survival: the effects of heart failure and race. The Journal
of clinical endocrinology and metabolism. Jun;98(6):2326-36.
on an annual basis in patients over 50 with goiter,
suspicious symptoms or raised antibody titres or with 6. Gencer B, Collet TH, Virgini V, Bauer DC, Gussekloo J, Cappola AR, et
al. Subclinical thyroid dysfunction and the risk of heart failure events: an
dyslipidaemia. individual participant data analysis from 6 prospective cohorts. Circulation.
Aug 28;126(9):1040-9.
Conclusion
7. Cappelli C, Rotondi M, Pirola I, Agosti B, Gandossi E, Valentini U, et al.
A complex pattern of interactions between thyroid TSH-lowering effect of metformin in type 2 diabetic patients: differences
metabolism and diabetes is well established and a between euthyroid, untreated hypothyroid, and euthyroid on L-T4 therapy
multifaceted cardiac link is evolving. Treating both patients. Diabetes care. 2009 Sep;32(9):1589-90.
thyroid function and diabetes early and aggressively 8. Wang C. The Relationship between Type 2 Diabetes Mellitus and Related
may offer cardiovascular risk reduction. Basal mech- Thyroid Diseases. Journal of diabetes research.2013:390534.
anisms controlling appetite and energy expenditure
is evolving. Increasing evidence suggests that insulin
sensitivity or drugs used to modulate it, will also af-
fect thyroid function. Better definition of interactions
between glucose metabolism and thyroid hormones
is necessary to optimize treatment of patients with
diabetes mellitus reduce heart disease risk.

Highlights

The prevalence of diabetes and thyroid dysfunction
remains high in the general population.
Common susceptibility genes confer risk for develop-
ment of both autoimmune thyroid disease and type
1 diabetes mellitus.
In hypothyroidism, insulin secretion is reduced; glu-
cose oxidation and glycogen synthesis are also de-
creased.

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