Spotlight on type 1 diabetes

A couple of significant studies in type 1 diabetes came out last month.

Researchers in Canada compared a traditional insulin pump, a single-hormone artificial pancreas (which delivered insulin based on a glucose sensor and algorithm) and a dual-hormone artificial pancreas (which added delivery of glucagon when glucose was low or falling) in patients age 12 and older with type 1 diabetes. For the randomized, crossover trial, published by The Lancet Diabetes and Endocrinology on Nov. 27, each patient stayed for 24 hours at the research facility on 3 separate occasions. Patients spent more of their time in the target glucose range (72 to 144 mg/dL or 4 to 8 mmol/L normally, up to 180 mg/dL or 10 mmol/L postprandial) on the single-hormone or dual-hormone artificial pancreas (62% and 63% of the time, respectively) than the insulin pump (51% of the time). The insulin pump was also associated with the most hypoglycemic events (52 events, 12 of them symptomatic), followed by the single-hormone pancreas (13 events, 5 symptomatic), and the dual-hormone pancreas (9 events, 0 symptomatic). There were 13 nocturnal hypoglycemic events with the insulin pump but none in either artificial pancreas group. This first head-to-head comparison of these systems shows that the artificial pancreas systems provide superior control to insulin pumps, that the addition of glucagon may reduce hypoglycemic events, and that the single-hormone artificial pancreas may be sufficient for overnight control, the researchers concluded. The results need to be confirmed in real-world settings and a more stable formulation of glucagon is needed, but studies such as this should encourage development, said an accompanying comment.

In another study, published in the Nov. 20 New England Journal of Medicine, researchers analyzed mortality rates in almost 34,000 Swedish patients with type 1 diabetes. Each patient was matched with 5 controls without type 1 diabetes, and they were all followed for an average of 8 years between 1998 and 2011. Their mean age at baseline was 35. Overall, 8% of the diabetic patients died, compared with 2.9% of controls. Mortality from cardiovascular causes was 2.7% and 0.9%, respectively. The increase in the mortality hazard ratio associated with diabetes went up as average HbA1c did: it was 2.36 for an HbA1c ≤6.9%, 2.38 for 7% to 7.8%, 3.11 for 7.9% to 8.7%, 3.65 for 8.8% to 9.6%, and 8.51 for an HbA1c ≥9.7%. Cardiovascular mortality followed a similar trend, and the results did not improve over time, with the excess risk being similar in 1998-2004 and 2005-2011. Even with good glycemic control, patients with type 1 diabetes have an increased risk of death, generally and from cardiovascular disease, the researchers concluded, noting that cancer deaths were not increased. Patients with worse diabetic control have even greater risk. The cause of this cardiovascular risk is unknown, they added. The study was limited by its observational nature and incomplete data on hypoglycemia, among other issues.