Background <p>For Diabetic polyneuropathy, the most prevalent form of polyneuropathy, there is a lack of evidence-based treatment options. Current approaches include pain management, alpha-lipoic acid, and antidepressants. Physical interventions, such as electrical stimulation (four-chamber galvanic bath) have been suggested but have limited supporting evidence. Heated granular stone therapy is another option to consider.</p> Methods <p>An unblinded randomized controlled trials was conducted in 68 diabetic patients with distal sensorimotor polyneuropathy undergoing rehabilitation for diabetes mellitus as a primary or secondary diagnosis in the Paracelsus-Harz-Clinic (Quedlinburg, Germany). Patients were randomized into either the intervention group receiving heated granulated stone footbaths, or the control group receiving four-chamber galvanic baths. The primary endpoint was the assessment of any change in polyneuropathy using a vibration sensation test (Rydel-Seiffer scale, 8/8) from admission to discharge, analyzed by t-test and multivariable regression. Additionally, serum TNF-α and IL-6 as potential markers for polyneuropathy were compared over time using paired t-test.</p> Results <p>The mean age of the patients was 66.8 ± 7.8&#xa0;years; 63.2% were male and mean BMI was 32.2 ± 6.4&#xa0;kg/m². Of the patients, 98.5% suffered from type 2 diabetes (one patient with type I diabetes); 82.4% were receiving oral antidiabetic medication; and 58.8% were insulin dependent. Distal sensorimotor polyneuropathy improved in both groups. The sum score increased from 16.7 to 22.6 in the study group and from 20.3 to 23.6 in the control group. A t-test showed a non-significant difference in the change of sum score between the treatment groups (2.6 points, <i>p</i> = 0.092), but adjusting for potential risk factors favors the intervention group (<i>p</i> = 0.043). Both analyzed markers decreased over time in each treatment group with IL-6 showing a clinical and significant reduction in the control group (<i>p</i> = 0.03).</p> Conclusion <p>Diabetic patients with distal sensorimotor polyneuropathy benefit from physical treatment with administration of electrical stimulation (four-chamber galvanic bath) or a therapy with heated granulated stones three times a week. Our results indicate that heated stone therapy may be a potential treatment option. However, further research is required to understand the underlying biological processes.</p> Trial registration <p>The study was registered in clinical trials.gov (identifier: NCT05622630, registration date: 18/11/2022).</p>