Positive affect predicts improved glycemic control and longevity in adults with type 2 diabetes. We tested DAHLIA, a self-paced online intervention for type 2 diabetes that teaches positive affect skills such as savoring, gratitude, and acts of kindness. Participants (n=49) were randomized to the 5-week DAHLIA course or an emotion-reporting waitlist control. DAHLIA was understood and accepted by participants and showed good retention (78%). At post-intervention, DAHLIA participants showed a significantly greater decrease in depression than controls (−4.3 vs. +0.6 points on the CES-D, p =.05). Secondary analyses found that this effect was considerably stronger in intervention recipients recruited online than those recruited in person. Intervention recipients recruited online also showed significantly increased positive affect, reduced negative affect, and reduced perceived stress. There were no effects on measures of diabetes-specific efficacy or sense of burden, or preliminary measures of health behaviors. This successful feasibility and efficacy trial provides support for a larger trial focusing more specifically on health behavior.

Increasing evidence suggests that positive affect plays an important role in adaptation to chronic illness, independent of levels of negative affects like depression. Positive affect may be especially beneficial for people in the midst of severe stress, such as the diagnosis of human immunodeficiency virus (HIV). As medical treatments for HIV have improved, the number of people living with HIV has increased, and prevention strategies tailored specifically to people living with HIV have become a priority. There is a need for effective, creative, client-centered interventions that can be easily disseminated to community treatment settings, but there are currently few established interventions for people who are newly diagnosed with HIV. We present the design and methods for a randomized trial in which we test the efficacy of one such skills-based intervention that targets positive affect as a novel mechanism of change. The proposed research builds on observational findings of the important unique functions of positive affect. We aim to determine whether a five-session theoryand evidence-based intervention designed to teach skills for increasing the frequency and intensity of daily positive affect does so, and whether this intervention has beneficial effects on subsequent psychological well-being, health behaviors, and physical health up to 15 months after diagnosis with HIV. This is a randomized controlled trial in a sample of adults recruited within 12 weeks of testing positive for HIV. The control group is attention-matched, and follow up assessments will be conducted immediately post intervention (approximately 5 months post diagnosis) and at 10 and 15 months post diagnosis. This study is an important next step in research concerning the adaptive functions of positive affect for people coping with HIV or other health-related life stress.

Background A very low–carbohydrate (VLC) nutritional strategy may improve glycemic control and weight loss in adults with type 2 diabetes (T2D). However, the supplementary behavioral strategies that might be able to improve outcomes using this nutritional strategy are uncertain. Objective This study aims to compare the impact of adding 3 different supplementary behavioral strategies to a web-based VLC diet intervention. To our knowledge, this is the first trial to randomize participants to different frequencies of dietary self-monitoring. Methods The study included 112 overweight adults with T2D (hemoglobin A1c ≥6.5%) taking no antiglycemic medications or only metformin. They received a remotely delivered 12-month VLC diet intervention. Participants were randomly assigned through a full factorial 2×2×2 design to supplementary strategies: either daily or monthly dietary self-monitoring, either mindful eating training or not, and either positive affect skills training or not. Our research goal was to determine whether 3 different supplemental strategies had at least a medium effect size (Cohen d=0.5). Results Overall, the VLC intervention led to statistically significant improvements in glycemic control (−0.70%, 95% CI −1.04% to −0.35%; P<.001), weight loss (−6.82%, 95% CI −8.57% to −5.08%; P<.001), and depressive symptom severity (Cohen d −0.67, 95% CI −0.92 to −0.41; P<.001). Furthermore, 30% (25/83) of the participants taking metformin at baseline reduced or discontinued their metformin. Only 1 Cohen d point estimate reached 0.5; daily (vs monthly) dietary self-monitoring had a worse impact on depressive symptoms severity (Cohen d=0.47, 95% CI −0.02 to 0.95; P=.06). None of the strategies had a statistically significant effect on outcomes. For changes in our primary outcome, hemoglobin A1c, the daily (vs monthly) dietary self-monitoring impact was 0.42% (95% CI −0.28% to 1.12%); for mindful eating, it was −0.47% (95% CI −1.15% to 0.22%); and for positive affect, it was 0.12% (95% CI −0.57% to 0.82%). Other results for daily (vs monthly) dietary self-monitoring were mixed, suggesting an increase in weight (0.98%) and depressive symptoms (Cohen d=0.47), less intervention satisfaction (Cohen d=−0.20), more sessions viewed (3.02), and greater dietary adherence (Cohen d=0.24). For mindful eating, the results suggested a benefit for dietary adherence (Cohen d=0.24) and intervention satisfaction (Cohen d=0.30). For positive affect, the results suggested a benefit for depressive symptoms (Cohen d=−0.32), the number of sessions viewed (3.68), dietary adherence (Cohen d=0.16), and intervention satisfaction (Cohen d=0.25). Conclusions Overall, our results support the use of a VLC diet intervention in adults with T2D. The addition of monthly (not daily) dietary self-monitoring, mindful eating, and positive affect skills training did not show a definitive benefit, but it is worth further testing. Trial Registration ClinicalTrials.gov NCT03037528; https://clinicaltrials.gov/ct2/show/NCT03037528