Randomized controlled study evaluating the effectiveness of a 3-week Schrothkur compared to a 3-week holiday stay in Oberstaufen specifically tailored to people suffering from type 2 diabetes mellitus

INTERVENTION: Intervention 1: 1. Schrothkur: 3‐week Schrothkur with four therapeutic elements (1) Schroth’s Diet (therapeutic fasting: light food, calorie‐reduced, mainly basic, fat‐ and animal protein‐free, almost salt‐free), (2) Schroth’s Body Pack (cold and damp body wrap to which the body responds with increased temperature and the excretion of metabolic residues) (15 times approx. 2 hours in the early morning), (3) Schroth's Drinking Regulation (change of drinking days and dry days, i.e. change of the daily amount of fluid intake, which should differ significantly on drinking days and dry days and which is determined by the spa physician individually by taking into account possible pre‐existing diseases; Kur drinks are herbal tea, mineral water, fruit juices, and, only by doctor's prescription, small amounts of dry wine), (4) daily change in higher body activities and rest days (drinking days are days with higher body activities (moderate sports activities such as hiking, golfing, Nordic skiing); dry days are rest days (relaxation exercises, massages, walks, resting, reading etc.); participation in the following events (obligatory): introductory talk by spa physician (1 hour); nutrition lecture (2 hours); "Gentle hiking" with a climate therapist (8 times; 2 hours); exchange of experience in the group moderated by a diabetes counselor twice a week (1.5 hours each); each participant will receive a pedometer for checking his/her daily exercise habits and to create an incentive for additional physical activity; a further optional activity includes personal meetings with the diabetes counselor Intervention 2: 2. Holiday stay directed specially at diabetics: 3‐week holiday stay specifically tailored to people suffering from type 2 diabetes mellitus and in compliance with the “Practical recommendations for nutrition and exercise” of the German Diabetes Society (DDG) and the German Society for Nutrition (DGE)” (the menus were coordinated with the diabetologist and the diabet CONDITION: E11.90 ‐ [generalization E11.9: Non‐insulin‐dependent diabetes mellitus; Without complications] PRIMARY OUTCOME: long‐term glucose parameter HbA1c in conjunction with taking diabetes‐related medicines at 6 months (antidiabetics, insulin) – pre, 2 weeks, post, 3, 6 months SECONDARY OUTCOME: pre, 2 weeks, post, 3, 6 months: ; Body Mass Index (BMI); blood pressure; diabetes‐related blood tests (fructosamine, CRP, HDL cholesterol, LDL cholesterol, triglycerides, creatinine, uric acid, TSH, GOT, GPT, GGT); well‐being (World Health Organization 5‐item Well‐Being Index – WHO‐5); general health / quality of life (EuroQol (EQ‐5D‐5L general health index);; pre, post:; analysis of VNS/HRV; ; pre, post, 6 months:; blood tests (C‐peptide, proinsulin); ; pre, 3, 6 months:; general health / health‐related quality of life (SF‐36); health‐related behavior; ; pre, 6 months:; days of sick leave (last 6 months); ; during the 3‐week Schrothkur:; daily documentation of physical activities, number of steps (pedometer), general condition, consumption of medicines INCLUSION CRITERIA: type 2 diabetes mellitus (medically confirmed diagnosis); HbA1c = 6,5% (48 mmol/mol); BMI = 27; participants were informed about the content and purpose of the study and gave their written informed consent