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Increased mortality risk associated with IGT mostly attributable to type 2 diabetes
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In the Chinese population, impaired glucose tolerance is associated with an increased morality risk, but a large amount of this elevated risk is driven by the subsequent onset of type 2 diabetes, according to recent findings.
Guangwei Li, MD, of the department of endocrinology at China-Japan Friendship Hospital, in Beijing, and colleagues conducted a follow-up analysis of the Da Qing Diabetes Prevention study on 542 participants (94% of the original cohort) in that study.
Guangwei Li
The Da Qing Diabetes Prevention study was a 6-year study, initiated in 1986, that randomly assigned 576 adults with baseline IGT to either a control group or one of three lifestyle intervention groups. Two follow-up studies, which were conducted in 2006 and 2009, followed participants with available data for 20 and 23 years after randomization. The researchers evaluated the incidence of diabetes, diabetes-related complications, mortality and causes of death. The mortality rate of participants was evaluated both before and after the onset of diabetes, and researchers also compared descriptive statistics between strata of patients based on the timeline of diabetes onset: within 10 years, 10 to 20 years, more than 20 years and no diabetes.
Over the 23-year follow-up, 32.1% of the study population died, the equivalent of 15.9 per 1,000 person-years. The majority of study participants (79%) developed type 2 diabetes.
Most of the deaths (74.7%) took place after the conversion to type 2 diabetes, equaling age-adjusted mortality rates of 11.1 per 1,000 person-years before and 19.4 per 1,000 person-years after the onset of type 2 diabetes.
Participants who progressed to type 2 diabetes within the first 10 years of follow-up had the highest cumulative mortality rate (37.8%) followed by participants with onset after 10 to 20 years (28.6%) and those who never developed diabetes or those who progressed to diabetes after 20 or more years of follow-up (13.9%). Participants with type 2 diabetes onset in the first 10 years, as well as those who developed diabetes between 10 and 20 years after enrollment, had significantly higher HRs compared with those who did not progress to diabetes or those who developed it later (onset within the first 10 years, HR = 3.87; 95% CI, 2.13-1.02; onset between 10 to 20 years, HR = 2.5; 95% CI, 1.3-4.81).
In an analysis adjusted for age, sex, intervention and other possible risk factors (ie, systolic blood pressure, smoking, cholesterol and history of cardiovascular disease), the researchers found that the onset of type 2 diabetes was associated with a 73% increased mortality risk (HR = 1.73; 95% CI, 1.18-2.52).
“This study is to our knowledge the first long-term, population-based cohort study of mortality related to IGT in China,” the researchers wrote. “IGT was associated with increased risk of death, but much of the increase was the result of the subsequent development of type 2 diabetes in many of those with IGT. The results provide a strong rationale for type 2 diabetes prevention in people with IGT because they indicate that the risk of death in people with IGT is much lower before than after the development of type 2 diabetes.” – by Jennifer Byrne
Disclosure: The researchers report no relevant financial disclosures.
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