Spotlight on diabetes prevention

Multiple recent studies looked at efforts to prevent diabetes among patients at risk for developing the condition.

The first study, published by the New England Journal of Medicine on June 7, was a trial of vitamin D supplementation in 2,423 adults who met at least two glycemic criteria for prediabetes (elevated glucose levels after fasting or glucose tolerance testing or an HbA1c level of 5.7% to 6.4%). They were randomized to either vitamin D3 at 4,000 IU/d or placebo regardless of baseline serum 25-hydroxyvitamin D level. After more than two years of follow-up, the study found that the vitamin D group had higher serum vitamin D levels but no significant difference in new type 2 diabetes cases, which developed in 293 patients in the vitamin D group and 323 taking placebo (9.39 vs. 10.66 events per 100 person-years, respectively; hazard ratio, 0.88 [95% CI, 0.75 to 1.04; P=0.12]). The study authors noted that two other trials published while this one was underway found similar results. One possible explanation for the lack of effect is the high percentage of study patients with adequate vitamin D levels at baseline, the authors said. An accompanying editorial pointed out that a post hoc analysis of the 103 patients with levels below 12 ng/mL did find a significant reduction in diabetes with supplementation. “Whether targeting populations with vitamin D levels below 12 ng per milliliter, many of whom have additional risk factors for diabetes, would have an effect on beta-cell function and progression to type 2 diabetes remains unresolved,” the editorial concluded.

Another study, published by BMJ Open Diabetes Research & Care on May 27, looked at use of people with type 2 diabetes as diabetes prevention mentors for at-risk patients. Researchers used a pool of 9,951 British people with type 2 diabetes to select, based on phone and in-person interviews, 104 mentors (mean age, 62 years; 55% men). A separate pool of 141,973 patients at high risk for diabetes was whittled down to 1,764 patients who were randomized to a suite of diabetes prevention methods, which included an intervention of clinicians supporting lifestyle change aided by the peer mentors. The mentors made 6,879 telephone calls to 461 participants; 73% of the mentors volunteered for at least six months and 63% for at least a year. The study authors concluded that patients with type 2 diabetes can be recruited, trained, and retained to support a group-based diabetes prevention program. “This volunteer model is low cost, and accesses the large type 2 diabetes population that shares a lifestyle experience with the target population. This is an attractive model for supporting diabetes prevention efforts,” the authors said. They did caution that the recruitment was time-consuming and that the cost-effectiveness of the program will not be analyzed until its effects on patient outcomes are known. Other caveats include that 65% of the mentors had some counseling or training before they were recruited.

Finally, a study published by JAMA Network Open on May 10 looked at how many U.S. adults at risk of diabetes are referred to prevention services and how many engage in them. Researchers used 2016 and 2017 National Health Interview Survey data from 50,912 adult respondents, 36.0% of whom had a diagnosis of prediabetes, an elevated diabetes risk score, or both. All were asked if they had received advice about diet or physical activity or referral to a weight loss or diabetes prevention program from a clinician. Among those with diagnosed prediabetes, 73.5% reported receiving advice and/or referral, and of those, 35.0% to 75.8% reported engaging in the respective activity or program in the past year. Among those with just an elevated risk score, the rates were 50.6% and 33.5% to 75.2%, respectively. “Participation in diabetes prevention programs was exceedingly low,” the study noted. Only 4.9% of patients with prediabetes and 0.4% of the risk-score group reporting being referred to such a program. “Our findings suggest that efforts to expand the supply of diabetes prevention LSM [lifestyle modification] programs are, at least now, insufficient, not being matched by uptake, or both,” the study authors said. They suggested that decision-support tools that encourage physicians to test, counsel, and refer at-risk patients may help increase uptake of these programs.