Randomized type 2 diabetes prevention trial addresses knowledge gap
medwireNews: Lifestyle intervention significantly reduces the risk for type 2 diabetes in people who have prediabetes based on fasting plasma glucose (FPG) or glycated hemoglobin (HbA1c) measurements, show findings from a randomized trial.
National diabetes prevention programs, such as those in the USA and the UK, admit participants based on elevated FPG or HbA1c levels, usually from a single measurement. Yet the intervention trials used as the basis for these programs were based on people with impaired glucose tolerance, and the belief that people categorized according to FPG or HbA1c will also benefit is an assumption with little solid supporting evidence.
Sampson and team have now addressed this information gap with the randomized Norfolk Diabetes Prevention Study (NDPS), which recruited people with two separate FPG tests initially of 110 mg/dL (6 mmol/L) or greater to less than 126 mg/dL (7 mmol/L), with the minimum threshold later reduced to 100 mg/dL (5.5 mmol/L), or one FPG test coupled with an HbA1c measurement of 6.0% or greater to less than 6.5% (≥42 to <48 mmol/mol).
“The effect size that we saw was about the same as the really big intense randomized controlled trials in impaired glucose tolerance patients,” lead study author Michael Sampson (Norfolk and Norwich University Hospital NHS Trust, UK) told medwireNews.
All these studies showed around a 40% risk reduction over 2 years, he said, “but our intervention was much less intense, and it was group-based and much less expensive.”
As reported in JAMA Internal Medicine, the intervention was similar to that used in national prevention programs, and involved six 2-hour educational group sessions over 12 weeks, followed by up to 15 maintenance sessions held every 8 weeks. The average cost per person was just US$ 153 (€ 129).
During an average follow-up of 24.7 months, 13.7% of 403 participants who attended at least one intervention session developed type 2 diabetes, as did 15.0% of 414 attending the same sessions and given additional telephone support from people with established type 2 diabetes.
By comparison, 22.8% of 171 participants who continued with usual care developed diabetes, giving estimated annual incidences of 6.4% and 7.1% versus 11.0%, respectively, equating to around a 45% reduced likelihood of intervention participants developing type 2 diabetes, even after additional adjustment for factors including duration of follow-up, age, BMI, and FPG.
There were no significant differences in participants’ likelihood of gaining benefit from the intervention according to their age, sex, BMI, or deprivation quartile.
The combined intervention group achieved an average 1.76 kg of weight loss at 12 months, which Sampson highlighted is similar to that reported by the UK’s national diabetes prevention program. “So it makes it very probable that the national program will also show benefit” in terms of diabetes prevention, he said.
The researchers had hoped that additional support from people with established type 2 diabetes, who share challenges and experiences with the study participants, would add value, but there was no significant difference in outcomes between the groups with and without this support.
“We think that’s probably because the effect size was already so big just with the standard intervention there wasn’t any room left to get an added change,” said Sampson. “But we may find something very different with the type 2 diabetes trial, which we’ll publish shortly.”
He explained that during screening, the team identified around 400 people with previously undiagnosed type 2 diabetes. These people were randomized into the same treatment groups as the people with prediabetes on the basis that they would also benefit.
This will be the subject of a forthcoming publication, with “some very interesting findings,” said Sampson, and implications for health policy.
“What we’ve got is an intervention that can apply both in prediabetes and in screen-detected type 2 diabetes – it’s an off-the-shelf program you can use across the spectrum.”
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