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Higher heart disease risk for diabetics with hypoglycaemia

Severe hypoglycaemia doubles risk of cardiovascular disease

Adrian O'Dowd

Wednesday, 31 July 2013

People with type 2 diabetes who have dangerously low blood sugar levels are at a much higher risk of cardiovascular disease, according to a study published online today in the BMJ.

An international team of researchers has found that that severe hypoglycaemia (the condition where a person has an abnormally low content of sugar in the blood) is associated with a two-fold increased risk of cardiovascular disease (CVD).

It has already been claimed in other research that severe hypoglycaemia is a potential risk factor for heart disease in patients with type 2 diabetes, but those studies’ findings have been questioned and some experts believe severe hypoglycaemia is merely a marker of co-morbid severe illness.

A team of researchers from Japan, the USA and the Netherlands carried out what they describe as the first systematic review to assess this association.

They analysed results from six relevant studies involving a combined study population of 903,510 patients.

Information on patients’ characteristics was taken, including their age, gender, duration of diabetes, CVD history, insulin use, body mass index and whether or not they were a smoker.

In total, 0.6% – 5.8% of participants experienced severe hypoglycaemia during a one to five years follow-up period.

Overall, this added just 1.56% to the total risk of developing heart disease in the whole population, but the link was consistent with all studies showing a positive correlation.

The researchers concluded that their results suggested “that severe hypoglycaemia is associated with a 2-fold increased risk of CVD”.

They argued that given this risk, avoiding severe hypoglycaemia could be important to prevent heart disease and “less stringent glycaemic targets may be considered for type 2 diabetic patients at high risk of hypoglycaemia”.

The association between heart disease and diabetics with hypoglycaemia had previously been explained by having one or more other serious illnesses, but the researchers said this was unlikely to be the cause.

They theorised that the prevalence of serious illnesses would need to be “unrealistically high” among patients who experienced severe hypoglycaemia and the association between serious illnesses and heart disease would need to be “extremely strong”.

To prevent heart disease in type 2 diabetes patients, they said it was important for clinicians to choose glucose lowering agents with a low tendency to induce hypoglycaemia, have good patient education, and self-monitoring of blood glucose to prevent hypoglycaemia.

DOI: 10.1136/bmj.f4533

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