Can a Heart-Healthy diet tame blood pressure in diabetes?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

INCLUSION CRITERIA: * Age 18 or older * Diabetes Mellitus Type 2 defined by HbA1c ≥6.5% or treatment of diabetes with diabetes medication(s) * Baseline systolic BP of 120-159 mmHg (based on average across 3 screening visits) * Baseline diastolic BP \<100 mmHg (based on average across 3 screening visits) * Willing and able to eat on site for one meal per day, 3 days per week, and eat only and all food provided as part of the study diets during the controlled feeding periods (run-in and four 5-week feeding periods). Note that actual frequency of on-site dining may be fewer than 3 days per week due to COVID-related restrictions, but participants will still need to be on site to pick up food and be weighed 3 days per week, and will still be expected to have meals monitored (in-person or remotely) for one meal per day, 3 days per week. * Willing and able to complete required measurement procedures * Have access to a mobile device or computer with video conference capabilities, or be willing to use a device for video conferencing provided by the study EXCLUSION CRITERIA: * Laboratory Exclusions * Serum potassium ≥5.2 mmol/L or \<3.5 mmol/L * Estimated glomerular filtration rate (eGFR) \<30 mL/min by commercial lab result (note that prior to 7/12/22, the lab was using the race-based Chronic Kidney Disease Epidemiology Collaboration (CKD EPI) equation, and on/after 7/12/22, the lab switched to using the CKD-EPI 2021 equation, which does not provide different estimated GFR by race)) * HbA1c\>9.0% * Medication Exclusions 1. Unstable dose (i.e., change in the 2 months prior to screening or prior to randomization) of any of the following: * Anti-hypertensive medications * Sodium-glucose co-transporter 2 (SGLT2) inhibitors or glucagon-like peptide-1 (GLP-1) receptor agonists * Stimulants, including oral medications for asthma or chronic obstructive pulmonary disease (COPD) * Hormone replacement therapy or thyroid hormone * Weight-increasing psychotropic agents, including antipsychotic agents, lithium, and mirtazapine 2. Use of any of the following medications: * Potassium supplementation in any form, including a multivitamin or electrolyte drink mix, with a dose \>99 mg/day, which is the allowable amount in over-the-counter products * Prandial or short-acting insulin * GLP-1 receptor agonist if on weight loss dose * Warfarin (Coumadin) * Chronic oral corticosteroid (intermittent use is okay) * Weight loss medications * Tirzepatide (Mounjaro) 3. Unwillingness to keep same dose of vitamin, mineral, and botanical supplements 4. Any medication not compatible with participation as determined by the investigators * Medical History Exclusions * Type 1 diabetes * Hypoglycemia requiring hospitalization or the assistance of another person in the last 12 months * Active cardiovascular disease or any event in the prior 6 months, including coronary artery bypass grafting (CABG), percutaneous transluminal coronary angioplasty (PTCA), myocardial infarction (MI), cerebrovascular accident (CVA), or congestive heart failure (CHF) exacerbation requiring hospital admission * Cancer diagnosis or treatment in the last 2 years (benign tumors or non-melanoma skin cancer or localized breast or prostate cancer not requiring chemotherapy is acceptable) * Active inflammatory bowel disease, bowel resection, malabsorptive syndrome, pancreatitis (episode within past year), history of Roux-en-Y gastric bypass, or history of other bariatric surgery that limits food intake volume or that requires a specific diet plan * Pregnancy or lactation or planned pregnancy * Any emergency department (ED) visit for asthma or chronic obstructive pulmonary disease (COPD) in the last 6 months * Any other serious illness or condition not compatible with participation as determined by the investigators * Physical Exclusions * Body weight \>420 pounds * Arm circumference ≥50cm * Weight loss or gain of \>5.0% of body weight during 2 months prior to screening, or large weight change during screening prior to randomization * Lifestyle and Other Exclusions * Significant food allergies, preferences, intolerances, or dietary requirements that would interfere with diet adherence * Not able to self-monitor glucose if needed * Consumption of more than 14 alcoholic drinks per week or consumption of more than 6 drinks on one or more occasion per week * Active substance use disorder that would interfere with participation * Participation in or planning to start weight loss program * Current participation in another clinical trial that might affect blood pressure or ability to comply with study procedures * Planning to leave area prior to end of study * Investigator discretion DASH4D-CGM ANCILLARY STUDY EXCLUSION CRITERIA: All DASH4D main trial participants will be invited to participate in the embedded CGM ancillary study. Participants with the following contraindications to wearing a CGM sensor will be excluded from the ancillary study: * History of allergic skin reaction to adhesive * Implantable pacemaker Note: Participants excluded from, or who do not wish to participate in, the CGM ancillary study are still allowed to participate in the DASH4D main trial if eligible.