Changes in family involvement occasioned by FAMS mobile health intervention mediate changes in glycemic control over 12 months.

Mobile phone-delivered interventions have proven effective in improving glycemic control (HbA1c) in the short term among adults with type 2 diabetes (T2D). Family systems theory suggests engaging family/friend in adults' diabetes self-care may enhance or sustain improvements. In secondary analysis from a randomized controlled trial (N = 506), we examined intervention effects on HbA1c via change in diabetes-specific helpful and harmful family/friend involvement. We compared a text messaging intervention that did not target family/friend involvement (REACH), REACH plus family-focused intervention components targeting helpful and harmful family/friend involvement (REACH + FAMS), and a control condition. Over 6 months, both intervention groups experienced improvement in HbA1c relative to control, but at 12 months neither did. However, REACH + FAMS showed an indirect effect on HbA1c via change in helpful family/friend involvement at both 6 and 12 months while REACH effects were not mediated by family/friend involvement. Consistent with family systems theory, improvements in HbA1c mediated by improved family/friend involvement were sustained.