Sweetch is a personalized mobile-health platform coaching system (mobile phone app) designed to promote adherence to physical activity guidelines for people with prediabetes.

The mobile phone app Sweetch seeks to increase leisure time physical activity rather than formal exercise through the use of a behavioral analytics engine that continuously process various aspects of the user's life habits, taking into account the user's demographics, behavioral change status, schedule, actual activity patterns, and more. The rationale behind this approach is that long-term adherence and patient engagement are more likely to be achieved when demands on manual user data entry are kept at a minimum. Compared to similar smartphone-assisted prevention apps, there are two novel features of the Sweetch app that may increase its efficacy. First, it uses a "just-in-time" adaptive intervention" approach that tailors recommendations to the user's day-to-day routine and his or her readiness for behavioral change. Second, and most importantly, it requires no direct involvement by the user, since all the necessary data is collected using built-in tracking pedometers, accelerometer and GPS (Global Positioning System) sensors on smartphones. In contrast, interventions that focus on dietary changes (i.e. calorie reduction, change in macronutrient content), require active user tracking at every meal, which is difficult to maintain in the long-term even with the use of sophisticated, electronic calorie counting tools. For these reasons, the Sweetch app may achieve greater long-term adherence, which is usually a limiting factor to efficacy of mobile health interventions.

Inclusion Criteria:

• Adults aged 18 -75 years with prediabetes (fasting BG 100-125 mg/dl, A1C 5.7% - 6.4%, or 2 hour BG of 140-199 mg/dl following 75-gram oral glucose tolerance test)
• Body mass index 24 - 40 kg/m2
• English speaker
• Smartphone user (Android or Apple 5s and above)

Exclusion Criteria:

• Currently doing more than 150 minutes/week of moderate/vigorous physical activity
• Presence of medical conditions that prevent adoption of moderate physical activity
• Use of any glucose-lowering or weight loss medications within the previous 3 months
• Current pregnancy (self-reported) or planning pregnancy during study period (self-reported)
• Presence of any condition that can result in spurious A1C readings (e.g. anemia [hemoglobin level below lower limit of normal] secondary to iron, vitamin B12, or folate deficiencies; hemoglobinopathies)
• Use of systemic glucocorticoids
• Use of antipsychotic medications (stable doses for at least three months of anti-depressants or anti-anxiety drugs will be allowed)
• Severe mental illness or learning disability
• Current participation in another clinical trial
• Liver enzymes >3 x upper limit of normal
• Poor literacy (REALM-R score of 6 or less)