This 2019 study followed 154 patients with type 2 diabetes or impaired glucose tolerance who were advised to substantially reduce sugar and starchy carbohydrates while eating more vegetables, low-glycemic fruit, meat, fish, eggs, dairy, nuts, and fats. After an average of two years, patients had lost 9.5 kg and reduced systolic blood pressure by 10.9 mmHg and diastolic pressure by 6.3 mmHg. Triglycerides fell 32%, HDL increased 8%, and the total cholesterol-to-HDL ratio improved 15%. ijerph-16-02680

These improvements occurred while patients were actually reducing their use of blood-pressure medication: 35 of the 163 antihypertensive prescriptions used at baseline were discontinued. The authors estimated that accounting for those medication changes would put the blood-pressure reduction closer to 14.8/8.1 mmHg. Perhaps most notable is how little the intervention required—basic dietary guidance, routine follow-up, and optional group support, conducted in an ordinary primary-care practice for a total research budget of just £7,000. The study was observational and participants self-selected the diet, so it cannot establish causation on its own, but it demonstrates what a relatively simple carbohydrate-restriction program can achieve in real-world clinical practice.

https://pmc.ncbi.nlm.nih.gov/articles/PMC6695889/pdf/ijerph-16-02680.pdf