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Risk of Severe Hypoglycemia in Type 1 Diabetes Over 30 Years of Follow-up in the DCCT/EDIC Study
Rose A Gubitosi-Klug1, Barbara H Braffett2, Neil H White3
1Case Western Reserve University, Cleveland, OH rose.gubitosi-klug@case.edu.
Insights
Intensive diabetes therapy initially increased severe hypoglycemia risk. Over 30 years, rates equalized between groups, highlighting persistent hypoglycemia challenges in type 1 diabetes management.
Area of Science:
- Endocrinology
- Metabolic Diseases
- Clinical Research
Background:
- The Diabetes Control and Complications Trial (DCCT) demonstrated intensive therapy (HbA1c ~7%) tripled severe hypoglycemia risk versus conventional therapy (HbA1c 9%).
- Long-term follow-up of the DCCT/Epidemiology of Diabetes Interventions and Complications (EDIC) cohort was conducted to assess persistent hypoglycemia rates.
Purpose of the Study:
- To investigate long-term rates of severe hypoglycemia in the DCCT/EDIC cohort after approximately 30 years of follow-up.
- To identify risk factors associated with severe hypoglycemia over time in individuals with type 1 diabetes.
Main Methods:
- Severe hypoglycemia events were reported quarterly during DCCT and annually during EDIC.
- Risk factors for severe hypoglycemia were analyzed over the study period.
Main Results:
- Half the cohort experienced severe hypoglycemia. During EDIC, rates decreased in the former intensive group but increased in the former conventional group, leading to similar rates (36.6 vs. 40.8 per 100 patient-years).
- A prior severe hypoglycemia episode was the strongest predictor of future events. Adolescent entry into DCCT and insulin pump use were associated with increased and decreased risk, respectively.
- Lower HbA1c levels correlated with increased severe hypoglycemia rates in both groups.
Conclusions:
- Severe hypoglycemia rates have converged between the DCCT/EDIC treatment groups due to increasing diabetes duration and similar HbA1c levels.
- Persistent severe hypoglycemia remains a significant, lifelong challenge for individuals with type 1 diabetes.
Objective:
During the Diabetes Control and Complications Trial (DCCT), intensive diabetes therapy achieving a mean HbA1c of ∼7% was associated with a threefold increase in the rate of severe hypoglycemia (defined as requiring assistance) compared with conventional diabetes therapy with a mean HbA1c of 9% (61.2 vs. 18.7 per 100 patient-years). After ∼30 years of follow-up, we investigated the rates of severe hypoglycemia in the DCCT/Epidemiology of Diabetes Inverventions and Complications (EDIC) cohort.
Research Design And Methods:
Rates of severe hypoglycemia were reported quarterly during DCCT and annually during EDIC (i.e., patient recall of episodes in the preceding 3 months). Risk factors influencing the rate of severe hypoglycemia over time were investigated.
Results:
One-half of the DCCT/EDIC cohort reported episodes of severe hypoglycemia. During EDIC, rates of severe hypoglycemia fell in the former DCCT intensive treatment group but rose in the former conventional treatment group, resulting in similar rates (36.6 vs. 40.8 episodes per 100 patient-years, respectively) with a relative risk of 1.12 (95% CI 0.91-1.37). A preceding episode of severe hypoglycemia was the most powerful predictor of subsequent episodes. Entry into the DCCT study as an adolescent was associated with an increased risk of severe hypoglycemia, whereas insulin pump use was associated with a lower risk. Severe hypoglycemia rates increased with lower HbA1c similarly among participants in both treatment groups.
Conclusions:
Rates of severe hypoglycemia have equilibrated over time between the two DCCT/EDIC treatment groups in association with advancing duration of diabetes and similar HbA1c levels. Severe hypoglycemia persists and remains a challenge for patients with type 1 diabetes across their life span.
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