Group-Based Lifestyle Intervention Linked to Type 2 Diabetes Risk Reduction

Michael Sampson, MD

Findings from a recent study suggested group-delivered lifestyle intervention to be low-cost and effective in reducing the risk of type 2 diabetes in patients with a high-risk glycemic category.

In a randomized clinical trial, dubbed the Norfolk Diabetes Prevention Study (NDPS), investigators found that group intervention with or without lay volunteers led to significantly lowers odds of type 2 diabetes, an effect which was consistent in all glycemic, age, and social deprivation groups.

The investigative team, led by Michael Sampson, MD, Department of Diabetes and Endocrinology, Norfolk and Norwich University Hospital National Health Service Trust, Norwich, England, conducted the parallel, 3-arm, group-based, randomized clinical trial from August 2011-January 2019 at 135 primary care practices and 8 intervention sites.

Following identification and screening of patients at increased risk of diabetes, they only included those with a high-risk glycemic category—defined as either an elevated fasting plasma glucose level alone (≥110 and <126 mg/dL) or an elevated glycated hemoglobin level (≥6.0% to <6.5%; nondiabetic hyperglycemia) with an elevated fasting plasma glucose level (≥100 to <110 mg/dL).

Sampson and colleagues noted that, in spite of this shift to HbA_1c criteria for categorizing risk and diagnosing type 2 diabetes, trial evidence for type 2 diabetes prevention is limited in this risk population.

“No prevention trial of more than 2 years’ duration has used HbA_1c as the diabetes diagnostic primary end point, in line with modern diagnostic practice, so the prevention evidence base does not align with current diagnostic approaches,” they wrote.

Thus, they randomized a total of 1028 patients to receive usual care (control; n = 178), a theory-based lifestyle intervention of 6 core and as many as 15 maintenance sessions (INT; n = 166), or the same intervention with the added support of diabetes mentors (INT-DPM; n = 426).

The intervention theory utilized for this study focused on maintenance of changes to activity and diet as well as emphasized patient-centered counseling techniques to encourage decision-making about behavior changes.

Diabetes mentors were assigned up to 7 participants in the INT-DPM cohort; the mentors contacted them to discuss progress, goal achievements, action planning, and barriers to coping.

Primary outcomes sought by the investigators was the incidences of type 2 diabetes, defined as paired HbA_1c data both ≥6.5%, or paired fasting glucose both ≥126 mg/dL.

Thus, over the course of the intervention period, a total of 156 participants progressed to type 2 diabetes, with 22.8% in the control group, 13.7% in the INT group, and 15.0% in the INT-DPM group.

Additionally, the investigators noted no significant differences between the INT and INT-DPM prevention arms in terms of the primary outcomes (odds ratio [OR], 1.14; 95% CI, 0.77-1.70; P = .51).

However, their results did show there to be a significant reduction in the primary end endpoint for each intervention group. As such, the odds of developing type 2 diabetes were significantly lower for the INT cohort (OR, 0.54; 95% CI, 0.34-0.85; P = .01) and the INT-DPM cohort (OR, 0.61; 95% CI, 0.39-0.96; P = .03). The odds for both interventions combined was similarly reduced (0.57; 95% CI, 0.38-0.87; P = .01).

Furthermore, after 12 months, the combined intervention group achieved significantly lower baseline-adjusted weight (–1.76 kg; 95% CI, –2.55 to – 0.97; P = .01), waist circumference (–2.48 cm; 95% CI, –3.67 to –1.29 ; P = .01), BMI (–0.59; 95% CI, –0.86 to –0.31; P = .01), and greater physical activity (metabolic equivalent of task minutes per week; P = .01) when compared with the control group.

They noted that a lower mean adjusted weight lost for the combined intervention group was maintained at 24 months (–1.47 kg; 95% CI, –2.64 to –0.30; P = .01).

In terms of cost, they reported that intervention costs per participant were low at $153.

“The NDPS confirms that prevention efforts in these current high-risk populations are effective, and aligns the evidence base with current practice,” Sampson and team wrote.

They noted that their materials and model are translatable and available to clinicians in practice, and further emphasized the ability of pragmatic group-based lifestyle interventions to reduce the risk of type 2 diabetes in these large populations currently being detected in primary care.

The study, “Lifestyle Intervention With or Without Lay Volunteers to Prevent Type 2 Diabetes in People With Impaired Fasting Glucose and/or Nondiabetic Hyperglycemia: A Randomized Clinical Trial,” was published online in JAMA Internal Medicine