**Background:** This is a narrative review article (Update 2023) from Austrian authors published in a German-language journal, addressing the intersection of obesity and type 2 diabetes mellitus (T2DM). The authors frame obesity as a chronic, progressive disease (per EASO's Milan Declaration 2015) and the single most important risk factor for T2DM given appropriate genetic predisposition. In the EU, 17% of adults aged 20–74 are obese and 36% are overweight. The combination of diabetes and obesity increases mortality risk 7-fold. The WHO has declared obesity the largest global chronic health problem, projected to affect approximately 60% of the world population by 2030.
**Methods:** This is a non-systematic narrative review. No formal search strategy, inclusion/exclusion criteria, or quality assessment methodology is described. The authors synthesize evidence from landmark clinical trials and epidemiological studies, referencing key studies including the Finnish Diabetes Prevention Study, the US Diabetes Prevention Programme, the Look AHEAD study, the DiRECT trial, the SCALE program (liraglutide), the STEP program (semaglutide), the SURPASS program (tirzepatide), and the STAMPEDE trial (bariatric surgery).
**Key Results:** The review reports that lifestyle intervention reduced diabetes incidence by 58% in both the Finnish Diabetes Prevention Study and the Diabetes Prevention Programme, with lifestyle outperforming metformin alone. In the DiRECT study, 46% of intervention participants achieved diabetes remission (mean diabetes duration 3 years, baseline HbA1c 7.7%). Each kilogram of weight loss in the first year after diabetes diagnosis was associated with 3–4 months of increased survival; 10 kg of weight loss restored 35% of the life expectancy lost after diabetes diagnosis (Lean et al.). A planned moderate weight loss of approximately 10 kg reduced mortality by about 25% in the Cancer Prevention Study 1. For pharmacotherapy: In SCALE Diabetes (623 patients), liraglutide achieved a mean 6% weight loss at 1 year, with 25% of patients achieving ≥10% loss. In STEP 2 (1,210 T2DM patients), semaglutide 2.4 mg weekly achieved a mean 9.6% weight loss at 68 weeks versus 3.4% with 1 mg; HbA1c reduction did not differ between doses. In SURPASS 1 (478 treatment-naïve T2DM patients), tirzepatide 5–15 mg achieved dose-dependent normoglycemia (HbA1c <5.7%) in 31–52% versus 1% with placebo, with mean weight loss of 7.0–9.5 kg. In SURPASS 5, tirzepatide 15 mg added to glargine ± metformin produced an additional HbA1c reduction of 1.47% and weight loss of 10.5 kg. For bariatric surgery, weight reduction of 15–40% of baseline weight is achievable, with diabetes remission rates of 45–95% depending on procedure type. The STAMPEDE 5-year follow-up confirmed sustained benefits.
**Clinical Implications:** The review advocates for a paradigm shift in T2DM management where weight is a co-primary treatment target alongside glycemic control. The authors recommend: (1) routine assessment of body composition (BIA, DEXA) and waist circumference in addition to BMI; (2) screening for sarcopenia using the SARC-F questionnaire; (3) preference for weight-neutral or weight-reducing antidiabetic agents (metformin, DPP-IV inhibitors, SGLT2 inhibitors, GLP-1 analogs) over weight-promoting traditional agents; (4) avoidance of weight-promoting concomitant therapies (psychotropics, steroids, beta-blockers) where possible; (5) use of structured meal replacement programs (LCDs, VLCDs) for short-term weight loss; and (6) consideration of bariatric/metabolic surgery for T2DM patients with BMI >35 kg/m², with mandatory lifelong multidisciplinary follow-up including bone density assessment at 2 years post-operatively. The authors caution that bariatric surgery does not constitute a 'cure' for diabetes, as recurrence or worsening can occur years later.