Diabetes prevention in the Caribbean using Lifestyle Intervention and Metformin Escalation (LIME): Protocol for a hybrid Type-1 effectiveness-implementation trial using a quasi-experimental study design

Background: Globally, several diabetes prevention interventions have been shown to be cost-effective, yet they have had limited adaptation, implementation, and evaluation in the Caribbean and among Caribbean-descent individuals, where the burden of type 2 diabetes is high. We report on the protocol for the Lifestyle Intervention with Metformin Escalation (LIME) study - an evidence-based diabetes prevention intervention to reduce the incidence of diabetes among Caribbean-descent individuals with prediabetes. Methods: LIME is a hybrid type-I effectiveness-implementation quasi-experimental study taking place in 4 clinical sites in Barbados, Trinidad, the U.S. Virgin Islands, and Puerto Rico. LIME targets individuals who self-identify as Caribbean or Caribbean-descent and have high-risk prediabetes with a hemoglobin A1c (HbA1c) between 6 and 6.4%. Eligible participants in the intervention arm are enrolled in a six-week lifestyle modification workshop. Six months later, individuals who have not lost at least 5% of their bodyweight or continue to have an HbA1c of 6% or higher are prescribed metformin medication. In total, participants are followed for one year. The primary effectiveness outcome is proportion of individuals who lower their HbA1c below 6%. Discussion: LIME is a unique diabetes prevention intervention for Caribbean and Caribbean-descent individuals. LIME utilizes a tailored lifestyle change curriculum, incorporates appropriate metformin prescribing when lifestyle change alone is insufficient, targets the highest-risk individuals with prediabetes, and is based in a clinical setting to ensure sustainability.