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Severe Hypoglycemia: Does the Risk Increase or Decrease with Longer Type 1 Diabetes Duration?

After 30 years of follow-up studies, DCCT/EDIC study gives findings regarding risk of severe hypoglycemia.

The use of intensive insulin therapy, an aggressive approach in the treatment of type 1 diabetes, decreases the risk of developing both macrovascular and microvascular complications. Despite recent advances made in the treatment of type 1 diabetes, severe hypoglycemia is still considered the most prominent and problematic adverse effect. In fact, the use of intensive insulin therapy to target an A1C of 7% showed an alarming threefold increase in the risk of suffering from severe hypoglycemia compared to conventional treatment in the original DCCT. Severe hypoglycemia is a medical emergency requiring treatment from a third party. When T1D Exchange suggested increased risk of severe hypoglycemia was associated with longer duration of disease, researchers began to evaluate the risk of severe hypoglycemia in the follow up studies of DCCT/EDIC.

Over 30 years ago, diabetes control and complications trial (DCCT) was conducted to evaluate treatment differences in intensive insulin therapy and conventional therapy. The group receiving intensive insulin therapy was given 3 or more injections of insulin and made adjustments based on frequent self-monitoring of their blood glucose levels. The group receiving conventional therapy was given 1 or 2 daily injections. During these trials, 1,428 patients reported all occurrences of severe hypoglycemia every quarter. After completion of DCCT, 1,394 patients went on to join the observational epidemiology of diabetes interventions and complications study (EDIC). These patients were asked to report all occurrences of severe hypoglycemia within 3 months of their annual follow up. Researchers evaluated these reports of severe hypoglycemia and converted them number of events per 100 patient years. Various risk models were used to detect a difference for the compiled DCCT/EDIC data.

Results from the original intensive treatment group of the DCCT showed a statistical difference and an increased rate of severe hypoglycemia compared to the conventional group. The results from EDIC revealed there was no longer a statistical difference between the two groups because there was an increase in the frequency of severe hypoglycemia in the conventional group and a decrease in frequency of severe hypoglycemia in the intensive treatment group (95% CI 0.91-1.35). Results from DCCT/EDIC also indicate that the study also evaluated the role of hypoglycemia in major accidents that occurred during the DCCT/EDIC, which resulted in hospitalization or death. Out of the 82 accidents, 41 were related to hypoglycemia as a possible, probably or principal cause.

The authors concluded that although initiation of intensive insulin therapy increased the risk of severe hypoglycemia, the risk between the two therapies will equalize as disease duration progresses. Rates of severe hypoglycemia during EDIC were found to be much lower than the rates found in DCCT, even when falling below an HbA1c < 7%. One very important limitation to consider in this study is the lack of real-time reporting of EDIC in comparison to DCCT. All severe hypoglycemic events were reported within the 3-month window of the annual follow up, which could have led to the underreporting of events. Despite these findings, clinicians and patients should still remain vigilant and strive to prevent severe hypoglycemia. Not only is severe hypoglycemia associated with negative health outcomes, but it can contribute to major accidents such as motor vehicle accidents.

Practice Pearls:

  • DCCT/EDIC study suggests that the risk and incidence of severe hypoglycemia decrease in disease duration; this conflicts with data presented in T1D Exchange.
  • There is a risk of severe hypoglycemia becoming a possible, probably or principle causes of major accidents.
  • Health care providers and type 1 diabetic patients continue to work towards reducing the risk of severe hypoglycemia.

References:

Gubitosi-Klug R, Braffett B, White N, et al. The Risk of Severe Hypoglycemia in Type 1 Diabetes Over 30 Years of Follow-up in the DCCT/EDIC Study. Diabetes Care. 2017. Epub 2017/05. doi: 10.2337/dc16-2723

Joanna Martinez-Mendez, PharmD Candidate 2018, Lake Erie College of Osteopathic Medicine School of Pharmacy: FL Campus