Type 2 diabetes mellitus has a genetic basis. Feelings of guilt are inappropriate here. A patient is not to blame if they develop type 2 diabetes mellitus. The majority of patients with type 2 diabetes mellitus are overweight. However, about 40% of overweight individuals never develop diabetes mellitus because they lack the genetic predisposition. A lean person with a genetic predisposition will develop type 2 diabetes only later in life. Due to the global increase in weight, the number of patients with type 2 diabetes mellitus is also rising, and patients are becoming increasingly younger. Therefore, the essential foundation of type 2 diabetes treatment is dietary modification aimed at weight reduction.
Therapy Requirements
In patients with obesity, an initial examination should be conducted before starting therapy. The initial examination consists of:
If there is a justified clinical suspicion of Cushing’s syndrome, a short dexamethasone suppression test may be performed.
For the dexamethasone suppression test, the patient takes 1 mg dexamethasone at 10 p.m. The following morning, between 8 and 10 a.m., the patient appears fasting for blood sampling, and cortisol is measured.
If cortisol is suppressed in this test, Cushing’s syndrome is excluded. The cut-off value depends on the laboratory and its method of determining cortisol, and is provided by the laboratory.
The patient’s motivation, willingness, and necessary resources for lifestyle changes should be assessed with regard to the therapy.
Overweight and obese individuals should engage in more physical activity. The increase in physical activity must be tailored to the patient’s state of health, and contraindications must be taken into account. Physical activity supports weight-loss efforts. In the aerobic range, an exercise program of at least 150 to 300 minutes per week should be carried out. The greater the exercise program, the greater the impact on body weight. Strength training should be performed twice per week. Strength training leads to muscle building. The increased muscle mass consumes energy even during rest periods and protects against renewed weight gain.
Crash diets, fasting, or restrictive diets lead to a loss of muscle mass and thus to a reduction in basal metabolic rate. This results in the so-called yo-yo effect, meaning that after ending the diet, significant weight gain occurs. To achieve long-term weight reduction, a permanent change in diet is necessary.
During each fasting phase within a diet program, basal metabolic rate is significantly reduced, and unfortunately, it does not increase again after the diet ends. This explains why people experience an increasingly pronounced yo-yo effect after multiple dieting attempts.
New eating behaviors must be learned, established long term, and should not be perceived as a loss of quality of life. The biggest mistake in weight reduction is eating less and eating poorly. Sustainable weight loss can only be achieved by eating better and more balanced. A low-fat diet and reduced alcohol consumption lead to weight loss. Fat is a flavor carrier, and Healthy fats (e.g., in olive oil/rapeseed oil) reduce the risk of heart attack and stroke – therefore, they should not and cannot be completely avoided. The right balance is crucial.
Weight loss is most effectively achieved by reducing overall energy intake. Therefore, in addition to fat and alcohol, the intake of carbohydrates and protein should also be reduced.
Not starving is the basic prerequisite for successful, long-term weight loss. Hunger arises from an empty stomach. To feel “happy,” one needs a feeling of satiety.
When food is consumed, the stomach stretches. This stretching stimulus activates the vagus nerve. In the hypothalamus, satiety-inducing neurotransmitters are released: norepinephrine, serotonin, GLP-1, CART, and α-MSH.
When the stomach empties, appetite-stimulating neuropeptides are activated in the hypothalamus: NPY, galanin, β-endorphin, MCH, anandamide.
Satiety does not depend on energy density, i.e., the number of calories per gram of food. Food should be low in energy but have a large volume to fill the stomach.
Low-energy foods include vegetables and salads – they can be eaten almost without restriction.
Liquid calories provide no satiety at all!! They pass through the stomach without any effect on gastric filling – they are “unnecessary” calories. Quickly absorbable carbohydrates from juices, sodas, cola, and iced tea (= high glycemic index) trigger a rapid and strong insulin release, leading to cravings. Therefore, liquid calories should be avoided!
Example: 250 ml coke has 105 kcal, A glass (240 ml) of freshly squeezed orange juice has about 110 calories, A 0.5-liter non-alcoholic beer typically contains between 100 and 125 calories.
An additional surplus of 100 kcal per day above daily requirements leads to a weight gain of about 6 kg within one year.
Alcohol contains many calories; therefore, its consumption should be limited, especially that of high-proof spirits. A 0.5 liter of beer contains an average of between 200 and 300 calories, depending on the type of beer.
Carbohydrates with a high glycemic index should generally be restricted throughout the day, because after large portions of these rapidly metabolized carbohydrates, there is a strong insulin release. The carbohydrates are quickly broken down, but insulin levels in the blood and brain remain elevated for a long time. This causes cravings and leads to the intake of snacks, which in turn provoke further insulin secretion.
Therefore, sugar should be replaced with sweeteners, and portion sizes of pasta, rice, potatoes, baked goods, and even fruit should be reduced.
In particular, avoiding carbohydrates in the evening (after 6 p.m.) is beneficial. Fat breakdown occurs mainly at night, but only if insulin levels are low. Insulin inhibits fat breakdown. The evening meal should therefore be high in protein, low in fat, and include plenty of vegetables and/or salad.
By reducing energy density, it is possible to save 300 to 500 kcal per day. This leads in the long term to significant weight reduction and an improvement in the lipid profile.
The above nutritional recommendations can be followed lifelong, lead to an energy deficit, and cause no health damage.*
These nutritional recommendations can be implemented with a Mediterranean diet. In a large randomized controlled trial, it was shown that a Mediterranean diet leads to weight reduction and also lowers the risk of cardiovascular mortality.
Finicelli M, Di Salle A, Galderisi U, Peluso G. The Mediterranean Diet: An Update of the Clinical Trials. Nutrients. 2022 Jul 19;14(14):2956. doi: 10.3390/nu14142956. PMID: 35889911; PMCID: PMC9317652.
https://www.ucsfhealth.org/education/guidelines-for-losing-weight
https://www.nhlbi.nih.gov/health/educational/lose_wt/recommen.htm
https://www.nhs.uk/better-health/lose-weight/
S V M, Nitin K, Sambit D, Nishant R, Sanjay K; (on behalf of Endocrine Society of India). ESI Clinical Practice Guidelines for the Evaluation and Management of Obesity In India. Indian J Endocrinol Metab. 2022 Jul-Aug;26(4):295-318. doi: 10.4103/2230-8210.356236. Epub 2022 Sep 16. PMID: 36185955; PMCID: PMC9519829.
https://www.nin.res.in/dietaryguidelines/pdfjs/locale/DGI07052024P.pdf
Anoop Misra a b c, Naval K. Vikram d, Amerta Ghosh a b, Piyush Ranjan d, Seema Gulati b c, India Obesity Commission Members 1 Revised definition of obesity in Asian Indians living in India Diabetes & Metabolic Syndrome: Clinical Research & Reviews
Volume 19, Issue 1, January 2025, 102989 Diabetes & Metabolic Syndrome: Clinical Research & Reviews https://doi.org/10.1016/j.dsx.2024.102989
https://www.nhs.uk/live-well/healthy-weight/managing-your-weight/tips-to-help-you-lose-weight/
Marc-André Cornier, MD, A Review of Current Guidelines for the Treatment of Obesity
Am J Manag Care. 2022;28(suppl 15):S288-S296. doi:10.37765/ajmc.2022.89292
Nicolai Worm: Glücklich und schlank, Münchner Verlagsgruppe GmbH, Riva, ISBN: 978-3-95814-227-5,
Erdmann J, Hausmann M, Bayer J, Satt essen und abnehmen: Das wissenschaftlich fundierte Erfolgskonzept auf Basis der Energiedichte – ohne Diät. Nach dem Konzept von Prof. Dr. Volker Schusdziarra, Münchner Verlagsgruppe GmbH, Riva, ISBN: 978-3-7423-1115-3.
GLP-1 Receptor Agonists
GLP-1 receptor agonists (GLP-1 RAs) were developed for the treatment of diabetes mellitus. Large randomized controlled trials have shown that they significantly reduce blood glucose levels and body weight. In addition, they lower cardiovascular risk and should therefore be preferred in patients with type 2 diabetes mellitus.
Depending on baseline blood glucose values, HbA1c can be reduced by 1 to 2% with GLP-1 RAs. GLP-1 analogs also support weight loss. Patients lose up to 15% of their body weight. When combined with dietary changes, even greater success in weight reduction can be achieved. Thus, GLP-1 RAs are particularly suitable for patients with severe obesity.
In diabetes therapy, the most commonly used agents are dulaglutide (Trulicity®), liraglutide (Victoza®), and semaglutide (Ozempic®). Dulaglutide and semaglutide are administered subcutaneously once a week.
GLP-1 RAs: Evidence of efficacy and safety
The main side effect of GLP-1 analogs is nausea, which decreases over time. Patients with diabetes mellitus have an increased risk of pancreatitis and pancreatic cancer. However, studies with dulaglutide, liraglutide, and semaglutide have so far provided no evidence that GLP-1 RAs increase this risk.
Diabetes Care 2021; 44(3): 765–773. DOI: 10.2337/dc20-1473. Epub 2021 Jan 4. PMID: 33397768; PMCID: PMC7896253.
The American Gastroenterological Association recommends pharmacotherapy in addition to lifestyle interventions for adults with overweight and obesity when lifestyle interventions alone are not sufficient for adequate weight reduction. Semaglutide at a dose of 2.4 mg and liraglutide at a dose of 3 mg are recommended.
Patients with overweight have an increased cardiovascular risk. Semaglutide has been shown to significantly reduce the risk of cardiovascular events in patients with pre-existing cardiovascular disease and diabetes (NNT 66) over a mean observation period of 40 months.
Liraglutide 3 mg (Saxenda®) and semaglutide 2.4 mg (Wegovy®) are approved for weight reduction in adults with comorbidities and a BMI > 27 kg/m², and in adults with a BMI > 30 kg/m² without comorbidities.
In a comparative study between liraglutide 3 mg and semaglutide 2.4 mg, patients lost 15.8% of their initial body weight (approximately 103 kg) with semaglutide and 6.4% with liraglutide. Treatment costs for Saxenda® and Wegovy® are normally not covered by health insurances.
Tirzepatide (Mounjaro®) is a combined GIP and GLP-1 receptor agonist. GIP is a gastrointestinal hormone that, like GLP-1, is released postprandially. Tirzepatide acts on both the GLP-1 and GIP receptors. Tirzepatide lowers blood glucose more effectively and, above all, reduces body weight. Like GLP-1 receptor agonists, it is administered subcutaneously once a week.
Obese patients (BMI > 30) lost 16% of their baseline weight with the 5 mg dose and 21.4% with the 10 mg dose after 72 weeks. The side effects are comparable to those of other GLP-1 receptor agonists. Tirzepatide is contraindicated in patients with familial medullary thyroid carcinoma or MEN2.
Mounjaro® is approved for weight reduction in adults with comorbidities and a BMI > 27 kg/m², and in patients with a BMI > 30 kg/m² without comorbidities. The starting dose is 2.5 mg once weekly and should be increased to 5 mg after four weeks. If necessary, the dose can be further increased in 2.5 mg increments every four weeks until the desired maintenance dose is reached, which may be 5 mg, 10 mg, or 15 mg. The maximum dose is 15 mg.
The treatment costs for Mounjaro® are covered by health insurance for the treatment of type 2 diabetes. If the drug is prescribed for weight management, however, it is considered a so-called “lifestyle medication” and is not reimbursable under statutory health insurance (GKV).
If conservative therapeutic options have been exhausted and weight reduction cannot be achieved, bariatric surgery should be considered.
Indications:
The effectiveness of bariatric surgery has been demonstrated in many studies. Weight reduction of 21–38 kg within one year and 15–28 kg even after ten years can be achieved.