Background:Body mass index (BMI)has increased in Latin-America, but the implications for the diabetesburden havenot been quantified. We estimated the proportion and absolute number of diabetescasesattributable to high BMI in Bolivia, Ecuador and Peru(Andean Latin-America), with estimation of region-level indicators in Peru.Methods: Weestimated the population attributable fraction (PAF) of BMI ondiabetes(regardless of type 1 or 2)from 1980 to 2014, including the number of cases attributable to overweight (BMI 25-<30), class I (30-<35),class II (BMI 35-<40) and class III(BMI ≥40)obesity.We used age-and sex-specific prevalence estimates of diabetes and BMI categories(NCD-RisC and Peru’s DHS survey)combined with relative risks from population-based cohortsin Peru. Findings: Across Andean Latin-Americain 2014, there were 1,258,313diabetes cases attributable to high BMI: 209,855 in Bolivia, 367,440in Ecuadorand681,018in Peru. Between 1980-2010, the absolute proportion of diabetes cases attributable toclass I obesity increased the most (from 12.9% to 27.2%) across the region. The second greatest increase was for class II obesity (from 3.6% to 16.5%). There was heterogeneity in the fraction of diabetes cases attributable to high BMI by region in Peru, ascoastal regions hadthelargestfractions,andso did high-income regions. Interpretation: Over one milliondiabetes cases are attributable to high BMI in Andean Latin-America. Public health efforts should focus on implementing population-based interventions to reduce high BMI and to developfocused interventions targeted at those at highest risk of diabetes.