Purpose The purpose of the study was to determine, through secondary analysis, whether the length of a couple's relationship and the participants' gender are associated with glycemic response to a type 2 diabetes (T2D) behavioral couples-based intervention. Methods A randomized trial was conducted to test the impact of a couples-level, telephone-based behavioral intervention on hemoglobin A1C in patients with T2D. One hundred and four patients and partners participated in the couples intervention arm, and 94 individuals participated in the individual arm. A1C levels were measured at baseline and 1-year follow-up. Results Results of the regression analysis showed that for men with T2D (n = 35) in the couples intervention group, longer length of relationship was associated with lower A1C at 1-year follow-up, after controlling for baseline A1C, diabetes duration, and income. Length of relationship was not significantly related to follow-up glycemic measures for women or men with T2D in the individual intervention. Conclusions Study findings suggests that for men with T2D in a couples-based intervention, those in longer relationships may be more likely to benefit from the intervention. More research is needed to better understand factors that contribute to successful couples-based behavioral approaches to help adults with T2D improve their glycemic control.