Background. The coexistence of type two diabetes (T2D) and cardiovascular diseases (CVD) in patients with overweight increases the risk of macro-vascular complications. Some studies are controversial of the results of Ramadan fasting (RF) in patients T2D+CVD. Objective: To compare different RF (antique and modern) on anthropometric, glycemic, blood pressure (BP), lipids, heel bone mineral density (HBMD), and ejection fraction (EF) in patients with T2D+CVD. Methods. An open, 60-day, controlled, single-center, randomized clinical trial included 51 patients (29 women) with T2D+CVD: 26 in Main (antique RF); 25 in Controls (modern RF). Primary endpoints: weight loss, fasting blood glucose and, blood insulin, BP. Secondary endpoints: blood lipids, HBMD, and EF. Results. Patients in Main lost weight ?8.02 kg (P<0.0001), in Controls lost weight ?2.67 kg (P<0.025); BMI in Main significantly decreased (P<0.0001), but in Controls did not significantly decrease (P>0.025). During a 30-day follow-up, Main did not regain weight and WC; but Controls regained weight and WC. In Main BP, all glycemic parameters (fasting glucose, immunoassay insulin, HOMA-IR), lipids (cholesterol, triglyceride, HDL), HBMD, and EF in patients with and without heart failure (HF) were significantly normalized at 30-day RF (P<0.0001). In Controls BP and all glycemic parameters significantly improved but they did not achieve normal (P>0.025). In Controls HBMD and EF in patients with HF did not change (P>0.025). At 30-day follow-up, glycemic, BP, lipids, HBMD, and EF parameters did not significantly change in Main; but in Controls they worsened as weight regained. Conclusion. Both the RF methods allowed weight loss, but antique RF led to markedly weight loss and significant positive change in glycemic, BP, lipids, bone mineralization, and EF in patients with T2D+CVD; the antique RF allowed patients to stop taking medications. The duration of the positive results depended on the maintenance of the achieved weight loss on RF.

The authors have declared no competing interest.

This research was supported by the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant for 2023-2026 years with trial registration AP23488544) with National Center for Scientific and Technical Information of the Republic of Kazakhstan. Kuat Oshakbayev, a PI of the project, and Altay Nabiyev are supported by University medical center for 2022-2024, and Medical Center ANADETO.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Ethical Committee of the University Medical Center (phone: +7 7172 69-25-86; Web: https://umc.org.kz/en/?ethics-commission=post-2; Email: mirgul.bayanova@umc.org.kz) approved the study (approval protocol #6 of 14.11.2022; monitoring and re-approval protocol #7/??, October-11-2023, project #2023/01-24. Board Affiliation: University Medical Center). The committee confirms that all methods were performed in accordance with the Declaration of Helsinki and guidelines of the Council for International Organizations of Medical Sciences (CIOMS) and that informed consent was obtained from all participants.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

The data are available from the authors upon reasonable request. Those wishing to request the study data should contact Principal Investigator of a research grant: Dr. Oshakbayev Kuat (Email: kuat.oshakbayev@umc.org.kz, phone + 77013999394).