Type 2 diabetes mellitus (T2DM) is the most expensive chronic disease in the U.S. Lifestyle modification is central to T2DM management, but long-term adherence to dietary recommendations is difficult. A key challenge is the difficulty of coping with cravings for high carbohydrate or sugar-laden foods in an environment where these foods are tempting and widely available. One mechanism by which mindfulness may increase long-term dietary adherence is by better equipping individuals with skills to experience food cravings and difficult emotions without eating in response. Such approaches seek to strengthen abilities to be non-judgmentally aware of, tolerate, and respond skillfully to food cravings and difficult emotions without reacting impulsively or maladaptively. The investigators hypothesize that improved ability to manage food cravings and emotional eating is a key mechanism through which mindfulness-enhancements can improve dietary adherence. The study will test a mindfulness-based intervention (MBI) for improving dietary adherence. Although the particular diet employed is not the focus of this study, the study will use a diet with about 10% of calories from carbohydrate as: (1) it induces a low level of ketone production, which will be used as a biomarker for dietary adherence; (2) prior studies suggest it improves metabolic parameters in T2DM, including glycemic control.
The study will use ecological momentary assessment (EMA) methods to measure eating in response to difficult emotions and/or food cravings. In the R61 phase, the team will ensure this measure is appropriate for further testing and assess the impact of the MBI components on our hypothesized behavioral mechanisms in N=60 persons with T2DM. The study plans 3 waves of 20 persons each with 12 weekly sessions. All participants will attend an in-person group course providing education on basic behavioral strategies for diet and physical activity. Participants will be randomized to receive this education alone (Ed) or this same material with added MBI components (Ed+MBI). The team will also pilot test two levels of intensity of maintenance phase intervention (monthly group meetings alone or supplemented by individualized attention) to prepare them for R33 testing. the investigators plan an R33 phase trial in which 120 persons with T2DM will be randomized (using a 1:2 ratio) to Ed or Ed+MBI conditions and followed for 12 months, including a 9-month maintenance phase. The study will test the robustness of the effect of MBI components on our proposed behavioral mechanisms, and on dietary adherence, as well as preliminary effect sizes on weight and glycemic control. The study will use an innovative adaptive intervention design to optimize maintenance phase intensity, which the investigators believe may be key to augment the MBI effects. The R33 phase will be registered and reported in a separate clinicaltrials.gov record.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
60
Education for carbohydrate-restricted diet
Mindful eating app-use and instruction
UCSF Osher Center for Integrative Medicine
San Francisco, California, United States
Frequency of Eating in Response to Cravings (Primary Mechanistic Outcome)
Percent of ecological momentary assessment (EMA) opportunities in which participants reported eating in response to food cravings over a 3 day period. EMA measures were delivered to cell phones 3 times each day. The final EMA measure each day included a second question about whether there were any instances of craving related eating not already reported earlier during the day. Thus there was an opportunity to report eating in response to cravings on 4 different EMA questions each day, a total of 12 potential measures over 3 days. The percent here uses the number of EMA responses received as the denominator.
Time frame: change from baseline to 6 months
Change in Impulsivity as Measured by Delayed Discounting Score
The 5-trial adaptation of the Delayed Discounting (DD; Koffarnus \& Bickel, 2014) is a decision-making exercise where individuals choose between a smaller, immediate reward and a larger, delayed reward. The task measures an individual's "discount rate," or how much they devalue a future reward compared to an immediate one, which is a a key aspect of impulsivity and self-control. Respondents choose between $100 delivered after a delay, or $50 available immediately. To derive estimates of discount rate, we used Mazur's hyperbolic discounting model (V=A/ (1+kD)18, wherein V is the discounted value of the delayed option, A is its objective amount, D is its delay, and k indexes the discount rate. We calculated values of k for each participant as the inverse of the indifference delay (1/ED50). We log transformed these values prior to analysis. Higher values of K indicate greater discounting, which reflects greater impulsivity.
Time frame: change from baseline to 6 months
Emotion-related Eating (Secondary Mechanistic Outcome)
Change in emotion-related eating as measured by the Coping subscale of the Palatable Eating Motives Scale (PEMS). The Coping subscale is comprised of 4 items rated on a scale from 1 (almost never/never) to 5 (almost always/always), with possible scores ranging from 4-20. Higher scores reflect worse coping/greater emotional eating. Thus, decreases over time reflect improved coping/decreased emotional eating.
Time frame: change from baseline to 6 months
Stress-related Eating (Secondary Mechanistic Outcome)
Change in stress-related eating as measured by two questions about stress-related eating from the MIDUS study. Possible scores range from 2-8. Higher scores reflect worse outcomes/greater eating in response to stress. Thus, decreases over time reflect improved outcomes/decreased stress-related eating.
Time frame: change from baseline to 6 months
Glycemic Control, Using HbA1c
Change in hemoglobin A1c (HbA1c) from baseline to 6 months by study arm
Time frame: change from baseline to 6 months
Fasting Glucose
Change in plasma fasting glucose from baseline to 6 months by study arm
Time frame: change from baseline to 6 months
HOMA-2IR Index of Insulin Resistance (Secondary Clinical Outcome)
Insulin resistance estimated from the Homeostatic model assessment (HOMA) model 2 index of insulin resistance. The basic formula is: (glucose × insulin) / 22.5, where glucose is measured in mmol/L and insulin in mU/L. The computer assisted re-calibration in model 2 addresses variations in the glucose resistance of the peripheral tissue and liver, increases in the insulin secretion curve for glucose \> 180 mg/dL, and contribution of circulating pro-insulin. Higher values indicate more insulin resistance (worse outcome). The Oxford University HOMA-2IR calculator was used (https://process.innovation.ox.ac.uk/software/p/2112/homa2-calculator/1). HOMA index values \< 2.0 are generally considered normal and indicate adequate sensitivity of cells to insulin. HOMA index values between 2.0 and 2.5 may indicate borderline changes in insulin sensitivity. HOMA index values \> 2.5 clearly indicate insulin resistance.
Time frame: change from baseline to 6 months
Weight Change(Secondary Clinical Outcome)
kilograms
Time frame: change from baseline to 6 months
Adherence to Diet as Measured by Fingerstick Blood Ketones
Adherence to diet as measured by average proportion of fingerstick blood ketones at or above 0.3 mmol/L at 24 weeks.
Time frame: 6 months
Diet Adherence by Mean Grams of Non-fiber Carbohydrate Consumed Per Day
Diet Adherence Between Intervention Arms as Measured by Mean Grams of Non-fiber Carbohydrate Consumed Per Day From 24- Hour Diet Recall
Time frame: change from baseline to 6 months
Perceived Stress
Perceived Stress Scale (PPS-10) total score. Scores can range from 0 to 40 with higher scores indicated greater perceived stress.
Time frame: change from baseline to 6 months
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