This study aimed to compare the frequencies of nuclear anomalies in buccal cells between diabetic and non-diabetic individuals and to assess the impact of a 'healthy diet'-a cornerstone in the treatment of diabetes. Seventy-six diabetic and 21 non-diabetic individuals participated in this parallel, randomised, intervention trial. All participants received information about the importance of a healthy diet, while participants randomly assigned to the intervention group received additionally 300g of vegetables and 25ml of plant oil rich in polyunsaturated fatty acids (PUFA) per day for 8 weeks. Cytogenetic damage in buccal cells was assessed at baseline and after 8 weeks using the buccal micronucleus cytome assay. Micronucleus (MN) frequency at baseline was significantly higher in participants with diabetes (0.58±0.30‰) compared with non-diabetic individuals (0.28±0.29‰). Further analysis of baseline data revealed significantly higher MN levels in participants of the highest tertile of waist circumference (+40%), fasting plasma glucose (+55%), glycated haemoglobin (+41%) and cardiovascular disease risk (+39%) relative to participants of the lowest tertile. The dietary intervention had no effect on MN frequencies. Glycated haemoglobin and biomarkers reflecting cytokinetic defect or acute cell death were reduced in both the intervention and 'information only' groups. The results of this study suggest a strong impact of abdominal obesity and glucose metabolism on genomic stability. Similar effects on nuclear anomalies were observed in the 'information only' group and the intervention group receiving vegetables and PUFA-rich plant oil.