Objective <p>To investigate the association between an almond-based low-carbohydrate diet (LCD) and continuous glucose monitoring (CGM) metrics in patients with type 2 diabetes mellitus (T2DM).</p> Methods <p>This was a prospective randomized controlled study. Hospitalized patients with T2DM from Changshu No.1 People’s Hospital were recruited from January 2022 to December 2022. 33 patients using CGM were included and randomly divided into the low-fat diet (LFD) group or the LCD with almonds group based on the random number table. Primary CGM metrics including time in range (TIR), time in tight range (TITR), time above range (TAR), time below range (TBR) were compared between the two groups. Linear regression analysis was performed to assess the association between diet group and nocturnal glycemic metrics.</p> Results <p>Compared to LFD group, patients in the LCD with almonds group had higher nighttime TIR [98.51% (95.83, 99.88) vs. 91.67% (89.52, 98.07), <i>P</i> &lt; 0.01] and TITR [94.14% (87.57, 98.41) vs. 77.58% (52.18, 90.58), <i>P</i> &lt; 0.05]. Nighttime TAR [0.00% (0.00, 0.00) vs. 1.39% (0.00, 7.95), <i>P</i> &lt; 0.01], HBGI [0.15 (0.01, 0.34) vs. 0.98 (0.08, 3.73), <i>P</i> &lt; 0.05], and SD (15.57 ± 6.21 mg/dL vs. 23.62 ± 9.12 mg/dL, <i>P</i> &lt; 0.05) were significantly lower in the LCD with almonds group. Multivariable regression demonstrated that LCD with almonds was independently associated with improvements in nocturnal TIR (<i>β</i> = 6.65%, <i>P</i> = 0.010) and TITR (<i>β</i> = 14.60%, <i>P</i> = 0.016) after adjustment for age, sex, and diabetes duration.</p> Conclusion <p>The almond-based low-carbohydrate diet improved nocturnal glycemic control in patients with type 2 diabetes. These improvements in nocturnal TIR and TITR remained significant after multivariable adjustment for age, sex, and diabetes duration.</p> Clinical trial registry <p>The study was registered at clinicaltrials.gov (registration no. ChiCTR2600116495).</p>