Silence Is Deadly for T2D with Hypos

Silent hypoglycemic episodes may correlate with asymptomatic episodes of ventricular arrhythmias, which might explain the risk of sudden death for patients with diabetes and cardiovascular disease during bouts of hypoglycemia, researchers suggested.

According to Markolf Hanefeld, MD, PhD, of Technical University Dresden in Germany, and colleagues, although patients identified only a few mild symptomatic episodes of hypoglycemia, continuous monitoring picked up a high frequency of these occurrences,

Additionally, patients did not report any arrhythmias, but continuous monitoring recorded numerous serious ventricular arrhythmias. The research team undertook the investigation because studies have shown that severe hypoglycemic events are associated with cardiovascular mortality. He and his colleagues therefore recruited 29 men and one woman who had been diagnosed with diabetes and documented cardiovascular disease.

The patients were continuously monitored with a Medtronic MiniMedGold device for interstitial subcutaneous glucose levels for 2 to 5 days and the Amedec ECGPro for 5 days.

Participants were about 68 years old, had average HbA1c levels of 7.3%, and were on stable insulin or oral antidiabetes medication.

Researchers demonstrated that periods of mild hypoglycemia – even episodes that were asymptomatic – were accompanied by bouts of ventricular arrhythmia.

Nineteen patients did not have a severe hypoglycemic event, defined as a level of less than 56 mg/dL (3.1 mmol/L). Any hypoglycemic event was defined as a level of less 70 mg/dL (3.9 mmol/L).

The mean number per patient of severe hypoglycemic events recorded by continuous monitoring was one, and the mean number of any hypoglycemic events was 2.60. Eleven severe events occurred during daytime, while 24 occurred at night.

When researchers scrutinized arrhythmias, they found that 17 patients experienced couplets, 10 patients had triplets, and five patients had bouts of ventricular tachycardia.

They demonstrated that in some of these cases the bouts of hypoglycemia and arrhythmias overlapped, but Hanefeld noted, "In this heterogeneous group of patients with a polypharmacy of cardiovascular drugs, we could not find a direct relationship between parameters of glycemic variability, quality of diabetes control, and risk of severe arrhythmias."

Hanefeld and colleagues did observe, however, that more of the ventricular arrhythmic events occurred during longer periods of hypoglycemia.

"Large scale prospective trials with continuous glucose monitoring and electrocardiography recording are needed to develop a risk score to single out patients at high risk for fatal arrhythmias," Hanefeld said.

Practice Pearls:

• The study suggests that patients with type 2 diabetes and cardiovascular disease on insulin or sulfonylurea treatment represent a high risk for silent hypoglycemia and arrhythmias.
• Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Hanefeld M, et al "Glycaemic fluctuations and arrhythmias in type 2 diabetes with cardiovascular disease" EASD 2012; Abstract 231.