Randomised controlled trialindependent cross-checkabstract checked★ key study I-INS-104 in-depth review

Long-term survival after intensive insulin treatment in type 1 diabetes

Association between 7 years of intensive treatment of type 1 diabetes and long-term mortality.

Overview

Writing Group for the DCCT/EDIC Research Group et al.. JAMA 2015 · PMID 25562265 · DOI 10.1001/jama.2014.16107

People who received intensive insulin treatment for about 6.5 years had about one third lower death risk 27 years later.

Does the study support the specific claim? No · Methodological quality: high

Study explained simply

What did the researchers want to find out?: Test whether intensive insulin therapy affects long-term survival.
How was the study done?: Follow-up of a randomised trial.
How many people, animals or samples were studied?: 1,441 young adults with T1D.
What was actually found?: 43 vs 64 deaths; HR 0.67.
How large was the observed effect?: -109 deaths per 100,000 patient-years.
What do the results mean in everyday life?: Good insulin treatment helps people with type 1 diabetes live longer.
What are the study's limitations?: Few deaths; later years observational.
What does it say about Elawady's specific claim?: Contradicts 'insulin does not treat diabetes'.
Do the results apply to Germany and Europe?: Applicable to Europe.
What can explicitly not be concluded from this study?: Cannot separate effects of later care.

Did 6.5 years of intensive insulin therapy affect mortality after 27 years?

Study design: Randomised controlled trial – Long-term observational follow-up (EDIC) of the randomised DCCT, analysed by original randomised group
Population: 1441 people aged 13-39 with T1D, 1-15 years duration, without major complications
Country: USA and Canada
Period: 1983-2012
Sample size: 1,441 (vital status 1,429)
Inclusion and exclusion criteria: Healthy volunteers with T1D; no hypertension or CVD at baseline

Results: 107 deaths: 64 conventional vs 43 intensive; absolute risk difference -109 per 100,000 patient-years (95% CI -218 to -1); HR 0.67 (0.46-0.99). Causes: CVD 22.4%, cancer 19.6%, acute diabetes complications 17.8%, accidents or suicide 16.8%. Higher HbA1c associated with mortality (HR 1.56 per 10% relative increase).
Absolute risks: -109 deaths per 100,000 patient-years (reported)
Authors' conclusion: 6.5 years of initial intensive therapy was associated with modestly lower all-cause mortality after 27 years.

Orienting tool: RoB 2
Type of assessment: simplified assessment (abstract only)
Full formal assessment: no
Overall risk of bias: low
Rationale: Randomised comparison preserved; some concerns about post-trial co-interventions.

HR 0.67 with upper CI 0.99 is borderline; absolute effect small but in a young cohort. Acute diabetes complications were 17.8% of deaths.

Better insulin treatment lowered long-term mortality; acute diabetes complications caused about one in six deaths.

Directly applicable; same biology and clinical standards in Europe.

Strong randomised-origin evidence that more effective insulin therapy improves survival in T1D.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	high
Risk of bias	low
Precision of results	moderate
Directness	direct
Reproducibility	partly replicated
Consistency with the overall evidence	consistent
Regional transferability	high
Adequacy of the interpretation (by the archive)	not applicable