Background: Diabetes mellitus (DM) is a metabolic disease characterized by impaired glycaemic control. We are familiar with the various types of DM and the different treatment options available. Nutrition is important for each type of DM. Objective: The objective of this study was to calculate daily energy and macronutrient intake in people with DM using three-day dietary records. Material and Methods: A total of 40 people with type 1 (45%) or type 2 (55%) DM completed a three-day dietary record. Daily energy and macronutrient intake were assessed using the Planeat nutritional application. Statistical analyses were performed using the two-sample t-test assuming unequal variances and one-way analysis of variance (ANOVA), with statistical significance set at p < 0.05. Results: The participants had a mean age of 48.33 ± 21.71 years, with an average body weight of 73.60 ± 22.07 kg and height of 168.43 ± 12.80 cm. Compared with the reference values, fasting plasma glucose, HbA1c and triacylglycerol concentrations differed significantly (p < 0.001), whereas no significant difference was observed for total cholesterol (p > 0.05). Dietary analysis showed lower intakes of carbohydrates (155.04 ± 50.49 g) and fats (59.94 ± 30.44 g), while protein intake remained within the recommended range (78.35 ± 31.94 g). Carbohydrates accounted for a lower proportion of total daily energy intake (43.03 ± 8.75%), whereas the contributions of fats (34.61 ± 9.39%) and proteins (22.36 ± 6.61%) were higher. However, none of these differences between the measured and recommended macronutrient intakes reached statistical significance (p > 0.05). Conclusions: Medical nutrition therapy remains a key component of DM management. These findings emphasize the importance of individualized dietary counselling aimed at improving macronutrient balance, dietary quality, and patient education to support glycaemic control and reduce the risk of diabetes-related complications.