['To determine whether dietary patterns associated with food insecurity are associated with poor longitudinal glycemic control.', 'In a prospective, population-based, longitudinal cohort study, we ascertained food security (Food Security Survey Module), dietary pattern (Healthy Eating Index-2005 [HEI 2005]), and hemoglobin A1c (HbA1c) in Puerto Rican adults aged 45-75 years with diabetes at baseline (2004-2009) and HbA1c at ∼2 years follow-up (2006-2012). We determined associations between food insecurity and dietary pattern and assessed whether those dietary patterns were associated with poorer HbA1c concentration over time, using multivariable-adjusted repeated subjects mixed-effects models.', 'There were 584 participants with diabetes at baseline and 516 at follow-up. Food-insecure participants reported lower overall dietary quality and lower intake of fruit and vegetables. A food insecurity*HEI 2005 interaction (P < 0.001) suggested that better diet quality was more strongly associated with lower HbA1c in food-insecure than food-secure participants. In adjusted models, lower follow-up HbA1c was associated with greater HEI 2005 score (β = -0.01 HbA1c % per HEI 2005 point, per year, P = 0.003) and with subscores of total vegetables (β = -0.09, P = 0.04) and dark green and orange vegetables and legumes (β = -0.06, P = 0.048). Compared with the minimum total vegetable score, a participant with the maximum score showed relative improvements of HbA1c of 0.5% per year.'] Are food-insecure dietary patterns associated with poor longitudinal glycemic control in diabetes : results from the Boston Puerto Rican Health study?