A fully provided, hypocaloric, carbohydrate-reduced high-protein (CRHP) diet compared to a hypocaloric conventional diabetes (CD) diet for 6 weeks improved glycemic control to a greater extent in face of an intended 6% weight loss in individuals with type 2 diabetes mellitus (T2DM). The present 24-week extension of that study reports on the efficacy of CRHP and CD diets in a real-life setting. Sixty-five individuals with T2DM who completed the initial 6-week fully provided diet period (% energy from carbohydrate, protein, and fat was 30/30/40 in CRHP, and 50/17/33 in CD) continued a free-living, dietician guided 24-week period of which 59 individuals completed. The CRHP compared to CD group reported a 4% lower carbohydrate intake and had higher urea excretion by 22% (both p ≤ 0.05) at week 30, suggesting less difference in carbohydrate and protein intake between groups during the 24-week extension compared to week 6. The loss of body weight during the initial 6 weeks was maintained in both groups during the 24-week extension (−5.5 ± 4.5 and −4.6 ± 4.8 kg) as well as HbA_1c (−8.4 ± 6.2 and −8.4 ± 6.9 mmol/mol) with no significant differences between groups. The additional benefits on glucoregulation harnessed by carbohydrate restriction under full diet provision for 6 weeks combined with titrated weight loss could not be maintained in a real-life setting of self-prepared diet aiming on similar diets for 6 months.