SAN FRANCISCO — Middle-aged patients with impaired glucose tolerance (IGT) who can delay their progression to type 2 diabetes by 6 years — usually by making lifestyle changes — have a lower risk of diabetes-related complications when they are in their 70s, Asian researchers report.
Guangwei Li, MD, China-Japan Friendship Hospital, Beijing, China, and team presented the 30-year findings from the Da Qing Diabetes Prevention Outcome Study as a poster and during an oral session here at the American Diabetes Association (ADA) 2019 Scientific Sessions, and Li outlined the results to assembled journalists during a press briefing.
Compared with participants who developed type 2 diabetes within 6 years of study enrollment, those who did not do so were 30% less likely to develop cardiovascular disease (CVD) (defined as stroke, myocardial infarction, or heart failure) and 58% less likely to develop microvascular complications (defined as neuropathy, nephropathy, or severe retinopathy) during the next 24 years.
The findings show that adults with IGT "have a very bright future, if you can delay diabetes for only 6 years," Li told Medscape Medical News.
Clinicians should advise normal-weight patients with IGT to restrict sugar and alcohol, he stressed, and encourage overweight or obesepatients to lose weight. Indeed, the study intervention meant that 32% of patients returned to normal glucose tolerance at the end of the trial.
"To see an effect like that 24 years after the end of the [6-year] intervention is remarkable," press briefing chair and coauthor of the current study, Edward W. Gregg, PhD, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, told Medscape Medical News.
Reasons for Findings Remain to Be Pinpointed
However, the reasons for these encouraging findings remain to be determined.
"Is it the behavior change and is that sustainable?" Gregg wondered. "Or were there structural changes in the community? Or was there some sort of long-term physiologic effect?"
In the meantime, "I think the interesting thing today," he said, "is the reminder that if you can [somehow delay progression to diabetes in high-risk patients] then "you have a big effect" on long-term health outcomes.
Indeed, the study confirms that "the long-term complications associated with IGT are much greater in people whose glucose tolerance worsens rapidly to diabetes," Li noted.
However, the good news is that "if that progression can be reversed or delayed for 6 years or more, the likelihood of developing long-term serious CVD and microvascular disease is much reduced," he said, echoing Gregg.
The findings, Li summarized, "further reinforce and are consistent with the thesis that the longer the progression to diabetes can be delayed, the fewer the complications."
Effects of Preventing Progression From Prediabetes to Diabetes
People with IGT are at increased risk of developing diabetes and related comorbidities, but it was unclear if stopping or slowing this process would improve these outcomes, Li explained.
To investigate this, researchers analyzed 30-year findings from the Da Qing Diabetes Prevention Study.
During 1986 to 1992, the trial enrolled 577 adults with IGT who lived in Da Qing, China, with a mean age of 46. One participant refused a baseline examination leaving 576 participants.
They were randomized to a control arm (138 participants) that received standard medical care or an investigation arm (438 participants) that received one of three interventions (diet or exercise or both) for 6 years.
The diet intervention was designed to promote weight loss among overweight or obese people and to reduce carbohydrate and alcohol intake in normal weight people.
The exercise intervention was designed to increase the amount of leisure-time physical activity.
In the current analysis, data from the three interventions were combined to provide sufficient statistical power.
At 6 years, 540 participants remained in the study.
By then, 252 participants (47%) had progressed to type 2 diabetes.
Of the participants who progressed to diabetes, 66% developed CVD and 44% developed microvascular disease during a 24-year follow-up.
Another 114 participants (21%) still had IGT at 6 years from study enrollment.
Fewer of these patients developed diabetes-related complications: 51% developed CVD and 31% developed microvascular disease during follow-up.
The remaining 174 participants (32%) regressed to normal glucose tolerance after 6 years.
In turn, fewer of these participants developed these complications: 46% developed CVD and 23% developed microvascular disease during follow-up.
Results Recently Published
"We just recently published a paper in Lancet Diabetes & Endocrinology," Li noted, which compared outcomes of all enrolled patients — the 438 participants in the intervention group versus the 138 participants in the control group.
That study showed that with the lifestyle intervention "CVD events were reduced by 26% and microvascular complications were reduced by 35%."
Overall, patients in the lifestyle intervention group lived an extra 1.5 years and were free of diabetes-related complications for an extra 5 years.
"The lifestyle intervention," Li added, "reduced the [cost of care] burden and increased quality of life."
The study was funded by the CDC, World Health Organization, China-Japan Friendship Hospital, and Da Qing First Hospital. The study authors have reported no relevant financial relationships.
ADA 2019 Scientific Sessions. Presented June 8 (abstract 1468-P) and June 10 (abstract 153-OR)
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