Purpose: To investigate whether adherence to the Dutch Healthy Diet index 2015 (DHD15-index) is associated with change in glycemic control and cardio-metabolic markers over two-year follow-up in people with type 2 diabetes (T2D). Methods: This prospective cohort study included 1202 individuals with T2D (mean age 68.7 ± 9.0 years; 62.5% male; mean HbA1c 53.8 ± 11.7 mmol/mol) from the Diabetes Care System cohort. Baseline dietary intake was assessed using a validated food frequency questionnaire, and adherence to the DHD15-index was estimated (range 0–130). HbA1c, fasting glucose, blood lipids (HDL and LDL cholesterol, cholesterol ratio), blood pressure, estimated glomerular filtration rate (eGFR), and BMI were measured at baseline, and after one- and two-year follow-up. Linear mixed model analyses were conducted to examine the associations between adherence to the DHD15-index and glycemic control and the cardio-metabolic outcomes, adjusting for energy intake, sociodemographic and lifestyle characteristics, and medication. Results: Highest adherence (T3) to the DHD15-index was not associated with change in HbA1c, compared to lowest adherence (T1) [βT3vsT1: 0.62 mmol/mol (− 0.94; 2.19), Ptrend = 0.44]. There was a non-linear association with fasting glucose, where moderate adherence (T2) was associated with a decrease in fasting glucose [βT2vsT1: − 0.29 mmol/L (− 0.55; − 0.03), Ptrend = 0.30]. Higher adherence to the DHD15-index was associated with a decrease in BMI [β10point: − 0.41 kg/m2 (− 0.60; − 0.21), Ptrend < 0.001], but not with blood lipids, blood pressure or kidney function. Conclusion: In this well-controlled population of people with T2D, adherence to the DHD15-index was associated with a decrease in BMI, but not with change in glycemic control or other cardio-metabolic parameters.