JMIR Publications

ABSTRACT

Background:

Adults with type 2 diabetes may experience health benefits, including glycemic control and weight loss, from following a very low-carbohydrate, ketogenic (VLC) diet. However, it is unclear which ancillary strategies may enhance these effects.

Objective:

The purpose of this pilot study was to estimate the effect sizes of three intervention enhancement strategies (text messages, gifts, and breath vs. urine ketone self-monitoring) that may improve outcomes of a 12-month web-based ad libitum VLC diet and lifestyle intervention for adults with type 2 diabetes. The primary intervention also included other components to improve adherence and well-being, including positive affect and mindfulness, as well as coaching.

Methods:

Overweight or obese adults (n=44, BMI 25-45 kg/m2) with type 2 diabetes (i.e., glycated hemoglobin (HbA1c) ≥6.5%), prescribed either no glucose-lowering medications or metformin alone, participated in a 12-month web-based VLC and lifestyle intervention. Using a 2x2x2 randomized factorial design, we compared three additional enhancement strategies: (a) near-daily text messages about the intervention’s recommended behaviors (texts n=22 vs. no texts n=22), (b) mailed gifts of diet-relevant foods and cookbooks (6 rounds of mailed gifts n=21 vs. no gifts n=23), and (c) urine- or breath-based ketone self-monitoring (urine n=21 vs. breath n=23). We assessed HbA1c and weight at baseline, 4, 8, and 12 months. We evaluated whether each enhancement strategy exerted a differential impact upon HbA1c and weight at 12 months against an a priori threshold of Cohen’s d ≥0.5.

Results:

We retained 73% of participants (n=32) at 12 months. The intervention, across all conditions, led to 12-month improvements in glucose control and reductions in body weight. In ITT analyses, the mean HbA1c reduction was 1.0% and the mean weight reduction was 5.3%, whereas among study completers these reductions were 1.2% and 6.3%, respectively, all with a P<.001. In ITT analyses, no enhancement strategy met the effect size threshold. Considering only study completers, two enhancement strategies showed a differential effect size of d ≥0.5: text messages (vs. no text messages) for HbA1c reduction and urine ketone self-monitoring (vs. breath ketone self-monitoring) for weight reduction. Cohen’s ds for gifts (vs. no gifts) were at least 0.2. Qualitative data suggested that participants generally liked the text messages and gifts, but found the breath meter difficult to use.

Conclusions:

Text messages, gifts of food and cookbooks, and urine-based ketone self-monitoring may potentially enhance the glycemic or weight loss benefits of a web-based VLC diet and lifestyle intervention for individuals with type 2 diabetes. Future research could investigate other enhancement strategies to help create even more effective solutions for type 2 diabetes treatment efforts. Clinical Trial: ClinicalTrials.gov NCT02676648