Obesity and Diabetes

The effectiveness of weight reduction in the treatment and prevention of type 2 diabetes has been proven by many studies. The effectiveness of weight reduction in the treatment and prevention of type 2 diabetes has been proven by many studies. In the “Finnish Diabetes Prevention Study”, the conversion of prediabetes to type 2 diabetes was reduced by 58% through lifestyle intervention [1]. Similar results were obtained in the “Diabetes Prevention Program” [2]. An English study showed that for every 1 kg of weight lost in the first year after diagnosis of type 2 diabetes, life expectancy increases by 3−4 months [3], and Williamson et al. [4] showed that a weight reduction of 10 kg reduces overall mortality in people with type 2 diabetes by 25%. In addition, weight reduction not only improves blood glucose levels, but also virtually all comorbidities of diabetes simultaneously (hypertension, fatty liver disease, depression, obstructive sleep apnoea syndrome (OSAS), etc.). However, these effects appear to be particularly strong when a weight reduction of at least 5% can be achieved [5]. Weight gain in type 2 diabetes treatment worsens cardiovascular risk factors and is associated with an increase in cardiovascular events and mortality [6].

The 2022 consensus report of the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) [7] defines a weight reduction of at least 5–15% as a treatment goal for most people with type 2 diabetes, with a 10–15% decrease even leading to diabetes remission [8]. As a general treatment goal, patients with obesity and diabetes should aim for weight stabilization in the range of the normal weight (body mass index [BMI] 18.5–24.9 kg/m²). The waist circumference of women and men should be ≤ 80 cm and ≤ 94 cm respectively [8] [9] ([Fig. 1]).

Fig. 1 Equivalent therapeutic goals in the treatment of type 2 diabetes.

The achievement of standard-compliant HbA_1c and weight values is therefore a consistent therapeutic goal of current guidelines, which should be used as a guide for blood glucose-lowering and other drug therapies of type 2 diabetes.

Nutritional therapy

The nutritional recommendations for obesity and type 2 diabetes are identical in the essential points and can be combined very well.

In order to properly structure a nutrition therapy, standardized action processes are necessary. The German-Nutrition Care Process (G-NCP) offers a very good basis for this.

Dietetic action competence is the central core of the G-NCP; it must be comprehensible and evaluable. The nutritional diagnosis according to a corresponding Problem-Etiology-Sign-Resources (PESR) system with reference to corresponding Nutrition-Care-Indicators (data from assessment) is the core of the planning of interventions and the corresponding nutrition therapy.

In the therapy of people with obesity and type 2 diabetes, the first step should be to implement the nutritional guidelines in the sense of a health-promoting diet.

The German Society for Nutrition (DGE) formulates guidelines for a health-promoting diet, which include what they call the “10 rules of the DGE” and allow sufficient individual leeway, as they do not stipulate rigid rules or prohibitions. Instead, they can provide a basic framework for intervention planning and implementation in therapy.

The 10 Rules of the DGE (2017):

1. Enjoy a variety of foods

2. Vegetables and fruits – eat 5 a day

3. Select whole grains

4. Supplement the selection above with animal products

5. Use healthy oils and fats

6. Reduce sugar and salt

7. It’s best to drink water

8. Cook with care

9. Eat mindfully and enjoy your meal

10. Mind your weight and stay active ([Table 1])

Table 1 General therapy goals for long-term weight stabilization.

Indicator	General therapy goal
Body mass index (BMI)	18.5–24.9 kg/m2
Waist circumference for women	≤80 cm
Waist circumference for men	≤94 cm

According to the current recommendations of the Diabetes and Nutrition Study Group (DNSG) of the EASD [10] a variety of dietary changes are recommended for weight loss. There does not seem to be any superiority of individual hypocaloric dietary patterns for weight loss, so that no specific pattern (reduced carbohydrate intake, increased protein content, low glycaemic index, Mediterranean or vegetarian dietary pattern) needs to be preferred. Overall, the most significant weight reduction is achieved by a very strongly reduced energy intake (formula diets, approx. 800 kcal/day) with meal replacements (complete or 1–2 meals/day) [11]. A significant initial weight loss in the first year is also associated with a higher probability of substantial weight loss in the long term. This is also of cardiovascular importance, as subgroup analyses of the Look AHEAD study were also able to demonstrate a reduction in cardiovascular events in these patients. In addition, such a concept with weight reduction of at least 15 kg, which is supported in the course of a multimodal maintenance strategy (including intermittent phases with the use of a formula diet), can induce a diabetes remission rate of about 70% after 24 months.

Overall, the current data do not indicate a clear superiority of a specific macronutrient composition with regard to weight loss. Therefore, it makes sense to include the individual assessment of current eating habits, preferences and metabolic goals for the distribution of macronutrients. However, in patients with obesity and type 2 diabetes, a short-term (12 weeks) increase in protein intake to 23–32% can be attempted for weight loss. Overall, a higher protein content seems to be slightly superior for weight loss [12]. If weight reduction is not required, the protein content should be between 10–20% at an estimated glomerular filtration rate (eGFR) > 60 mg/ml per 1.73 m² . This should be increased to 15–20% from the age of 65. In contrast, a protein intake of 10–15% is recommended for poorer kidney function.

The main source of dietary fats should be vegetable food and preferably consist of monounsaturated and polyunsaturated fatty acids (nuts, seeds, fish, oils (olive, rapeseed, soybean oil)). This leads to an improvement in glucose metabolism, fatty liver disease, and cardiovascular risk. In addition, it is recommended to reduce the consumption of saturated and trans fatty acids to<10% or<1% of total energy intake. At the same time, the consumption of nuts, seeds, legumes [beans, peas and lentils], fruits and whole grains should also increase the fibre content to more than 35 g/day. Fibre consumption can also be increased by additive supplements if it is not possible to achieve the desired fibre intake.

For patients with type 2 diabetes who do not achieve their blood glucose therapy goals or who want to avoid an escalation of drug-based diabetes therapy, reducing the total carbohydrate intake with low-carbohydrate or very low-carbohydrate diets may therefore be a viable approach. As long as the recommendations regarding the intake of proteins, fibre and fats are adhered to, a variable carbohydrate intake is possible here. However, very low-carbohydrate (<40% of energy intake) or carbohydrate-rich (>70% of energy intake) dietary patterns should be avoided, as large observational studies have shown increased mortality in this regard. In addition, extreme carbohydrate reduction in type 2 diabetes leads to an increased incidence of hypoglycaemia and ketoacidosis.

When advising patients with diabetes, a key strategy for achieving blood glucose targets should include an assessment of the current food intake, which requires keeping a dietary journal. This should be followed by individual guidance on self-monitoring the carbohydrate intake.

In all the therapy efforts, it is important for the patient to maintain his or her enjoyment of food. It is equally important for the patient to receive encouragement, for example about the choice of food, and practical tools for daily food planning. The motivation for a healthy, balanced diet should always be framed by the guidelines of diabetes and obesity nutrition therapy. The focus on maintaining the quality of life and positive self-esteem can be aided by nutritional behaviour (portion sizes, meal frequency, food and drink selection) in addition to the recommendations of limited sucrose intake (World Health Organization [WHO] recommendation<25 g/day). Epidemiological studies suggest that the replacement of sucrose with calorie-free sweeteners (saccharine, aspartame, stevioside, etc.) in sweetened beverages has a beneficial effect on body weight and cardiovascular risk factors.

Multimodal therapy approach

Large intervention studies on conservative weight loss measures, such as the Counter-Balance study (COUNTERacting BetA cell failure by Long term Action to Normalize Calorie intakE) or the DiRECT study, showed that people with obesity and type 2 diabetes mellitus were able to achieve type 2 diabetes remission through weight loss and long-term weight stabilization [13]. Longer-term data from the Look-AHEAD study also show that mean weight gain and glucose metabolism parameters were also better with intensified lifestyle modification compared to standard 3−4 consultations per year, but this was not reflected in a difference in the primary cardiovascular endpoint [14]. Interestingly, however, even the control group with 3−4 standard consultations per year showed some weight loss over the course of the study and not, as would be epidemiologically expected, further weight gain. It can be concluded from this that a successful treatment strategy for weight reduction in people with type 2 diabetes should always start early and, especially in the long term, include at least 3−4 lifestyle consultations per year.

Specific treatment objectives

Therapy goals should be individually tailored to the patient and, in particular, take into account comorbidities and cardiovascular risk factors. For people with obesity and type 2 diabetes without other concomitant diseases and without cognitive impairment, the recommendations of the National Healthcare Guidelines can be used [15].

Components of the multimodal therapy approach

Conservative measures of lifestyle modification form the basis of obesity therapy. The coordinated implementation of nutritional, exercise and behavioural therapeutic interventions in an interdisciplinary team is crucial ([Fig. 2]). As part of a nutritional medical intervention, first, eating behaviour is assessed. Following this, the ingested number of calories is reduced in a controlled manner and the composition of food is optimized against the background of concomitant diseases (see section “Nutritional Therapy”). In addition to traditional training sessions, grocery shopping together and cooking courses are held with the patients. Within the framework of behavioural therapy support, the first step is a structured analysis of possible factors (stress, emotions, psychiatric pre-existing conditions, concomitant diseases, etc.) that have a negative impact on eating behaviour, i. e. hyperalimentation. In the course of further treatment, these factors are then specifically addressed by behavioural therapy (e. g. learning coping strategies, stimulus control, learning of flexibly-structured vs. rigid eating/activity behaviour, etc.). Proper and long-term adherence of the patient is crucial for the therapeutic success of multimodal obesity therapy. Standardized, partly commercial, weight loss programs follow this multimodal approach exactly and should therefore be actively offered and recommended to patients with obesity and diabetes.

Fig. 2 Components of a multimodal therapy concept for people with obesity and diabetes.

Physical activity

Regular physical exercise helps to prevent weight gain. Several studies have shown that people with an active lifestyle and sufficient physical activity can more easily achieve weight stabilization [16]. The duration and type of physical activity should be determined individually.

The current recommendations of the ADA on physical activity can be found in a publication by ElSayed et al. [17]. The main components are:

• Most adults with type 2 diabetes should get at least 150 minutes of moderate to vigorous exercise per week, spread over at least 3 days/week, with no more than 2 consecutive days of no activity.

• For younger and physically fitter individuals, shorter periods (at least 75 minutes/week) of intense or interval training may also be sufficient.

• Adults with type 2 diabetes should do strength training 2 to 3 times a week on non-consecutive days.

• All adults, especially those with type 2 diabetes, should reduce the amount of time they spend on sedentary activities each day. Long periods of sitting should be interrupted every 30 minutes for 3 to 6 minutes.

• Physical activity should be integrated into a multimodal program. Interventions should include a high frequency of counselling (≥16 sessions over 6 months) and focus on dietary changes, physical activity and behavioural strategies to achieve an energy deficit of 500–750 kcal/day.

Drug therapy for patients with diabetes and obesity

In the current EASD/ADA consensus report, antidiabetic drugs are stratified according to their effectiveness. First choice therapeutics are substances with very high (semaglutide, tirzepatide) or high (dulaglutide, liraglutide) weight-reducing effects. Sodium-glucose cotransporter-2 (SGLT2) inhibitors are not primarily recommended, but are preferred to metformin and dipeptidyl peptidase 4 (DPP-4) inhibitors for weight loss.

Metformin

The data on weight loss with metformin over the longest period of time was obtained from the Diabetes Prevention Program. In the first 3 years of this double-blind, randomized study, patients on metformin lost an average of 2.9 kg (placebo 0.4 kg). The effects lasted up to 15 years. In a direct comparison of metformin with 2nd or 3rd generation sulfonylureas, a meta-analysis showed a mean difference in weight of − 3.86 kg ((95% CI − 5.18; − 2.53 kg), n=3185, 4 studies, I 2=69%) in favour of metformin therapy [18]. In studies in untreated patients with type 2 diabetes, weight change in the metformin study arms was +1.5 to − 2.9 kg. Weight loss was also reported in 3 studies compared to DPP-4 inhibitors (mean difference in weight between − 0.7 and − 2.2 kg). The 3 individual studies involving 3 different active ingredients were not combined into a meta-analysis.

GLP-1 receptor agonists

Glucagon-like peptide-1 (GLP-1) receptor agonists lower body weight primarily through a reduction in appetite. Inhibition of gastric emptying may play an additional but subordinate role. In various clinical studies in patients with type 2 diabetes, the mean weight reduction with GLP-1 receptor agonist therapy was approximately 3 kg. A meta-analysis of 25 studies (exenatide, liraglutide 1.8 mg) in overweight and obese patients with and without diabetes showed a weight loss of up to 2.8 kg (with diabetes) and 3.2 kg (without diabetes) respectively [18].

Liraglutide at a dosage of 3 mg/day has been approved for the treatment of obesity (BMI>27 kg/m² with concomitant disease or BMI>30 kg/m²) in Germany. The approval is based on data from the SCALE study program. Mean weight loss with 3 mg/day liraglutide was approximately 8.4 kg at 56 weeks compared to 2.8 kg with placebo [19].

Semaglutide once a week is the most effective GLP-1 receptor agonist currently approved in Europe in terms of weight loss. In the STEP-1 study (Semaglutide Treatment Effect in People with Obesity), weight reduction with semaglutide 2.4 mg 1×weekly and concomitant lifestyle intervention was 14.9% at 68 weeks (treatment policy estimand versus placebo group 2.4%) [20]. With an average starting weight of 105 kg, this corresponds to a weight loss of 15.3 kg. More than one-third of the subjects in the Verum group in the STEP-1 study lost at least 20% of their baseline weight. In addition, the analysis of secondary endpoints also suggests an improvement in cardiometabolic risk factors. In the USA, semaglutide 2.4 mg 1×weekly was approved for the treatment of obesity as early as June 2021 (Wegovy). In January 2022, semaglutide 2.4 mg 1×weekly also received approval from the EU Commission for the indication of obesity. The approval was extended to children and adolescents aged 12 and over at the beginning of 2023.

In the Phase 3b STEP 8 study, the efficacy of liraglutide 3 mg/day was evaluated in direct comparison with that of semaglutide 2.4 mg 1×weekly. Participants lost an average of 15.8% of their body weight with semaglutide, but only 6.4% with liraglutide (1.9% with placebo). In addition, significantly more patients with semaglutide than with liraglutide achieved weight reductions of at least 10%, 15% or 20% [21].

SGLT2 inhibitors:

SGLT2 inhibitors inhibit SGLT2 in the proximal renal tubule, through which 90% of glomerular-filtered glucose is reabsorbed, thereby increasing renal glucose excretion. This results in an energy loss of approximately 250−300 kcal per day and allows weight reduction. However, weight reduction is limited by possible compensation mechanisms. As further mechanisms of weight loss, an increased rate of lipolysis or an activation of energy-consuming gluconeogenesis by glucagon release stimulated by SGLT2 inhibitors have been discussed. In insulin-treated patients, insulin dose reduction on co-medication with SGLT2 inhibitors also contributes to weight loss. The SGLT2 inhibitors approved for antidiabetic therapy cause a dose-dependent moderate weight loss of approximately 1.5−2 kg (placebo-adjusted). The weight loss is initially more pronounced and usually ends on a new plateau after about 26 weeks.

Incretin co-agonists

Results from several studies to date confirm the potential of the dual glucose-dependent insulinotropic polypeptide GIP/GLP-1 incretin agonist tirzepatide to reduce HbA1c and body weight in people with type 2 diabetes. Data from the randomized, double-blind, Phase 3 study of the efficacy and impact of tirzepatide (SURPASS-1) show that tirzepatide leads to a significant reduction in HbA1c after 40 weeks of use (− 2.07% at the 15 mg dose vs. +0.04% at placebo). The majority of participants achieved HbA1c levels below 7% (87% in the 5 mg dose, 92% in the 10 mg dose, and 88% in the 15 mg dosage versus 20% in the placebo group). Together with the reduction in blood glucose, weight reductions of 7.9% (5 mg), 9.3% (10 mg) and 11.0% (15 mg) were achieved, which correspond to a weight reduction of 9.5 kg (− 0.7 kg with placebo) at a baseline weight of 85.9 kg (BMI 31.9 kg/m²) at the highest dosage [22].

In the head-to-head SURPASS-2 study, tirzepatide was double-blindly compared with semaglutide 1 mg over a period of 40 weeks. In all three doses (5, 10, 15 mg), tirzepatide was superior to semaglutide in terms of glucose-lowering and weight-reducing effects [23]. In May 2022, it was approved in the USA for the indication of type 2 diabetes. Data from the cardiovascular endpoint study SURPASS-CVOT are not yet available; they are expected at the end of 2024.

Results from the Phase 3 SURMOUNT-1 study in patients with overweight and obesity (excluding type 2 diabetes), published in June 2022, show that participants treated with tirzepatide achieved dose-dependent weight loss of 16% (5 mg), 21.4% (10 mg) and 22.5% (15 mg) over 72 weeks. More than half of patients taking tirzepatide 10 mg and 15 mg (55% and 63%, respectively) lost at least 20% of their body weight, compared to only 1.3% with placebo [24]. In the SURMOUNT-2 study (obesity and type 2 diabetes), participants achieved a mean weight reduction of 13.4% (13.5 kg) with tirzepatide 10 mg and 15.7% (15.6 kg) with tirzepatide 15 mg, compared with 3.3% (3.2 kg) with placebo. In the second primary endpoint, 81.6% (tirzepatide 10 mg) and 86.4% (tirzepatide 15 mg) of participants achieved at least a 5% reduction in body weight, compared with 30.5% with placebo.

The proportion of participants with an HbA1c value below 5.7% (50.2% (tirzepatide 10 mg) and 55.3% (tirzepatide 15 mg) was also higher than in the placebo arm (2.8%) [25].

Approval for the treatment of obesity with/without type 2 diabetes is pending in the United States and Europe.

Metabolic surgery

For people with type 2 diabetes, especially if they are obese, surgical therapy can be a useful supplement to conservative therapy. For the treatment of type 1 diabetes or other forms of diabetes, metabolic surgery is not recommended because there is insufficient data on efficacy and safety. The therapeutic principle of metabolic surgery has only developed in recent years on the basis of randomized studies in which surgical therapy of type 2 diabetes was superior to conservative strategies in terms of weight reduction, diabetes remission and improvements in glucose metabolism.

Importance

Metabolic surgery refers to surgical procedures in the field of obesity surgery, where the indication does not exclusively depend on weight, but also the treatment of type 2 diabetes. The main goal of surgical therapy is to improve the glycaemic metabolic control. For other obesity-associated diseases such as arterial hypertension, lipid metabolism disorders or non-alcoholic fatty liver disease, there is currently insufficient data to establish the indication for metabolic intervention primarily because of these diseases. For most people with type 2 diabetes, metabolic surgery will not be the first choice in therapy concept escalation. This is mainly due to the fact that modern antidiabetic drugs and modified insulin therapies offer safe and long-term effective diabetes therapy with a good quality of life. At the same time, however, patients with type 2 diabetes, who can especially benefit from surgical treatment of diabetes, should be informed about this therapeutic option. The benefits of timely metabolic surgery should always be weighed against the risks.

Indication

At the “2nd Diabetes Surgery Summit Consensus Conference”, experts from surgery and diabetology proposed a therapy algorithm for people with type 2 diabetes ([Fig. 3]) [25]. According to the current S3 Guideline, the indication for metabolic surgery in people with type 2 diabetes and a BMI≥35 kg/m² can be given in Germany if diabetes-specific individual target values cannot be achieved [27]. A BMI≥of 40 kg/m² and above can be used as a primary indication for metabolic surgery in people with type 2 diabetes, even if the parameters of blood glucose control and the complexity of drug therapy for diabetes are not taken into account.

Fig. 3 Algorithm for making therapy decisions for metabolic surgery in people with type 2 diabetes. The decision tree is based on the proposal of the 2nd Diabetes Surgery Summit Consensus between different disciplines. BMI = body mass index. Data according to [26].

The indication for a metabolic intervention should be determined jointly by diabetologists and surgeons (especially if the BMI is<40 kg/m²). It is also recommended to perform metabolic interventions only at a centre with special expertise.

Surgical methods

In metabolic surgery, procedures from obesity surgery are used (e. g. laparoscopic Roux-en-Y gastric bypass or sleeve gastrectomy), although there are no general recommendations for a standard surgical procedure. When making individual therapy decisions, the advantages and disadvantages of surgical therapy procedures must be considered in order to achieve the therapeutic goals and avoid complications ([Table 2]). The choice of procedure is individualized according to S3 Guidelines and takes into account the patient’s initial weight, concomitant diseases, the patient’s wishes, the technical feasibility of the procedure, etc.

Table 2 Advantages and disadvantages of various procedures in diabetes surgery. Data according to [27].

Procedure	Advantages	Disadvantages
Sleeve gastrectomy	Good risk-benefit ratio, also possible in the very high BMI range (e. g. as two-stage concept)	Inferior to RYGB in terms of long-term weight control, reflux control and diabetes remission
Proximal Roux-en-Y gastric bypass (RYGB)	Good control of reflux disease, superior to the sleeve gastrectomy in terms of type 2 diabetes remission	Increased morbidity compared to the sleeve gastrectomy with the same mortality, risk of dumping syndrome, ulcers and internal hernias
Mini gastric bypass (MGB)	Lower perioperative morbidity than RYGB, since only one anastomosis	Increased risk of malabsorption with long biliopancreatic diversions, risk of dumping syndrome and internal hernias, potential bile reflux into the gastric pouch

BMI: body mass index.

Side effects

Risks of bariatric surgery

The well-established therapeutic benefit of metabolic surgery must be weighed against the risks of this therapy when making individual therapy decisions. It should be borne in mind that, in contrast to conservative obesity management, there are very effective and safe drug therapies for the treatment of type 2 diabetes, although these options are not always consistently exhausted. The main side effects of antidiabetics include gastrointestinal complaints (e. g. metformin, GLP-1 receptor agonists), weight gain and an increased risk of hypoglycaemia (sulfonylureas, insulin). However, these adverse effects of pharmacotherapy are very rarely life-threatening, while the perioperative mortality of bariatric surgery is between 0.1−0.3%. In addition to acute surgery complications (e. g. pulmonary embolism, fistulas of the staple suture, bleeding, anastomosis insufficiency), metabolic surgery can also increase the risk of micronutrient deficiency, skin wrinkles, weight gain, addiction, suicidal tendencies and suicides in the long term [28] [29].

International consortia such as the Longitudinal Assessment of Bariatric Surgery (LABS) or others with case numbers of more than 15 000 surgically-treated obese people with type 2 diabetes have found a 30-day mortality rate of 0.1−0.3% and severe complications in 2.3−4.3% associated with the procedures. The main risk factors for the occurrence of serious adverse events are a history of leg vein thrombosis and pulmonary embolism, obstructive sleep apnoea syndrome and extremely high body weight. The decisive measure for reducing the risk of long-term adverse effects of metabolic surgery is structured, long-term follow-ups of patients ([Table 3]).

Table 3 Bariatric operations require lifelong aftercare. Post-operative information according to S3 Guideline Surgery of Obesity and Metabolic Diseases (Version 2.3 (February 2018) AWMF Registry No. 088–001). Data according to [27].

Scope of aftercare

Control of the weight development Adjustment of medication for concomitant diseases Assessment of eating habits and appropriate advice Encouragement to participate in physical activity Check for implementation of a supplement for the prophylaxis of Deficiency symptoms due to malnutrition or malabsorption Laboratory controls Screening for mental illnesses Recognizing complications and initiating appropriate interventions or Indication of necessary/recommended further operations Encouragement to participate in self-help groups Information on avoiding pregnancy in premenopausal women in the first 2 years

Antidiabetic medication

Diabetic metabolic control is significantly improved upon completion of the operation. It is therefore important to ensure that the antidiabetic medication is adjusted. Medications with a risk of hypoglycaemia should be paused (sulfonylureas) or significantly reduced (insulin).

Insulin

The insulin requirement decreases with increasing insulin sensitivity. In practice, reducing the insulin doses by about 20−50% (basal insulin, bread unit factor) has been proven. Close blood glucose monitoring is necessary. The insulin doses should be titrated so that the fasting blood glucose value is 80−110 mg/dL (4.4–6.1 mmol/l). If the basal insulin dose in patients with type 2 diabetes falls below 0.1−0.2 U/kg body weight, this therapy can be discontinued. Should the use of prandial insulin in type 2 diabetes patients also be necessary postoperatively, the altered kinetics of glucose absorption argues for the use of short-acting insulin analogues. It is imperative to continue insulin therapy in patients with type 1 diabetes.

15−20% of insulin-treated patients with type 2 or type 1 diabetes develop diabetic ketoacidosis within the first 48 h to 2 months postoperatively. In most cases, this is caused by inadequate insulin administration. Continued basal insulin administration is therefore particularly important in type 1 diabetes.

Metformin and SGLT2 inhibitors

In the first 6 months after bariatric surgery there is a significant increase in ketogenesis [30]. The risk of lactate acidosis or ketoacidosis is thus increased. To date, there are no studies on the frequency of lactate acidosis with metformin or euglycaemic ketoacidosis with SGLT2 inhibitors after bariatric surgery. Nevertheless, according to the current information on both drugs, a pause in the first 6−12 weeks is recommended.

Since SGLT2 inhibitors lead to osmotic diuresis, the risk of dehydration is increased postoperatively.

GLP-1 receptor agonists and DPP-4 inhibitors

For both drug classes, structured studies in post-bariatric patients are lacking. However, small studies indicate that the efficacy of GLP-1 receptor agonists is not significantly reduced despite elevated endogenous GLP-1 levels. The use of DPP4 inhibitors is especially useful early postoperatively due to the low side effect spectrum.

Summary

Weight reduction strategies are part of the basic therapy for people with obesity or type 2 diabetes. People with type 2 diabetes should be motivated to eat a healthy and balanced diet and increase physical activity. Targeted weight reduction is also an escalation step in therapy for patients with type 2 diabetes. When choosing drug therapy for type 2 diabetes, preference should be given to active ingredients (metformin, GLP-1 receptor agonists, SGLT2 inhibitors) that enable weight reduction. Since weight reduction for people with obesity or type 2 diabetes is difficult to achieve through conservative therapeutic strategies, metabolic surgery has developed into the therapy alternative for patients with type 2 diabetes and a BMI>35 kg/m² in recent years. Compared to conservative type 2 diabetes therapy, metabolic surgery is significantly more effective in terms of weight reduction, long-term weight stability and blood glucose reduction, but is also associated with higher acute and long-term risks.

Conflicts of Interest

JA received honoraria for scientific collaboration, speakers bureau, and advisory boads from Amgen, Astra Zeneca, Boehringer Ingelheim, Bayer, Lilly, Novartis, Novo Nordisk, rhythm pharmaceuticals.
AL declares the following conflicts of interest: Travel expenses: Lilly Germany and Novo Nordisk; research support: Astra Zeneca; advisory board activities: Novo Nordisk.
SM declares having received travel support from NovoNordisk, Lilly and Biomarin.
SMM declares the following conflicts of interest: advisory boards and lecture for: Amarin, Astra Zeneca, Bayer, Boehringer Ingelheim, Daichii-Sankyo, esanum, Ipsen, Lilly, Novartis, Novo Nordisk, Sandoz, Sanofi. Institutional research funding: Daichi-Sankyo, Lilly, Novo Nordisk, Takeda.
MM declares receiving travel expenses and lecture fees form Novo Nordisk.
LS has no conflicts of interest.
MB has received lecture and consulting fees from Amgen, Astra Zeneca, Boehringer-Ingelheim, Daiichi-Sankyo, Lilly, Novartis, Novo Nordisk and Sanofi.

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Publication History

Article published online:
07 March 2024