PURPOSE OF REVIEW: This review aims to investigate the relationship between dietary changes and the microbiome in patients with diabetes and colorectal cancer (CRC). The link between CRC and type 2 diabetes is momentous, as individuals with diabetes have a 40-60% higher risk of developing CRC and often experience lower survival rates. However, limited studies explore how diabetes may contribute to the progression to CRC through changes in the microbiome. By clarifying these connections, this review summarizes mechanisms in type 2 diabetes and CRC through microbiota pathways, presenting evidence from clinical trials regarding nutritional interventions for treating both conditions. We will focus on how nutritional components can alter the gut microbiome, highlighting the potential role of nutritional adjustments as adjuvant therapy for patients with diabetes who are facing precancerous or cancerous conditions. RECENT FINDINGS: There is growing evidence about the interactions between the microbiome and the causes of diabetes and CRC. Both conditions are characterised by changes in the gut microbiome, known as dysbiosis, which involves alterations in specific bacteria, such as Bifidobacterium, Bacteroides, Akkermansia, Faecalibacterium, Ruminococcus, and Fusobacterium. It is important to consider dietary modifications to address dysbiosis, malnutrition, glycemic variability, and inflammation underlying these conditions. Consuming a higher amount of fermentable carbohydrates alongside a lower amount of fermentable proteins can positively influence the microenvironment that regulates insulin secretion and bile acids, as well as an increase in short-chain fatty acids. This may be beneficial for patients with diabetes and CRC. However, it is also important to consider potential interactions between food and medication as well as gastrointestinal tolerability.