Introduction: The efficacy of iGlarLixi, a fixed-ratio combination of basal insulin glargine 100 units/mL (iGlar) and the short-acting GLP-1 RA lixisenatide (Lixi), was established in people with type 2 diabetes (T2D) who were advancing therapy from oral antidiabetic drugs (OADs) and basal insulin (BI). This retrospective study aimed to evaluate the effectiveness and safety of iGlarLixi using real-world data from people with T2D in the Adriatic region countries. Methods: This was a non-interventional, retrospective, multicenter, cohort study with the collection of pre-existing data at iGlarLixi initiation and after 6 months of treatment in real-world clinical and ambulatory settings. The primary outcome was the change in glycated hemoglobin (HbA1c) at 6 months after iGlarLixi initiation. Key secondary outcomes included the proportion of people achieving HbA1c < 7.0%, the effect of iGlarLixi on fasting plasma glucose (FPG), body weight and body mass index (BMI). Results: In this study, 262 participants (130 in Bosnia and Herzegovina, 72 in Croatia and 60 in Slovenia) initiated treatment with iGlarLixi. The participants had a mean ± SD age of 66.2 ± 7.9 years and the majority were women (58.0%). The mean baseline HbA1c was 8.9 ± 1.7% and the mean body weight was 94.3 ± 18.0 kg. After 6 months of treatment, the reduction in the mean HbA1c was statistically significant (1.11 ± 1.61%, 95% confidence internal [CI] 0.92, 1.31; p < 0.001), and the proportion of participants who achieved HbA1c < 7.0% had significantly increased from baseline (8.0–26.0%, p < 0.001). The change in mean FPG (mmol/L) levels was significant (2.7 ± 4.4 [95% CI 2.1, 3.2; p < 0.001]). The mean ± SD body weight and BMI were significantly reduced by 2.9 ± 4.3 kg (95% CI 2.3, 3.4; p < 0.001) and 1.3 ± 4.4 kg/m2 (95% CI 0.7, 1.8; p < 0.001), respectively. Two serious hypoglycemia episodes and one adverse gastrointestinal effect (nausea) were registered. Conclusions: This real-world study demonstrated the effectiveness of iGlarLixi for improving glycemic control and decreasing body weight in people with T2D who need to advance therapy from OADs or insulin.