The metabolic and hormonal impact of rapid dietary changes in type 2 diabetes has not been clarified. The objective of this study was to test whether a short-term, low-fat diet affected metabolic control, insulin sensitivity, lipids and adipocyte hormones in patients with type 2 diabetes with hypertriacylglycerolaemia. Nineteen outpatient subjects (10 M, 9 F) with type 2 diabetes and triacylglycerols >2.2 mmol/L at screening were included in the study. Dietary intake was assessed by weighing during two periods of 3-day baseline diet followed by a 3-day low-fat dietary intervention. The two periods of baseline diet did not differ with respect to relevant variables during intervention. Subjects were advised to increase fibre-rich and low-fat foods and to decrease intake of visible fat in an isoenergetic manner. The percentage of energy from fat was reduced from 39 to 22 (p < 0.0001), median values. Daytime blood glucose did not change and fasting insulin and fasting glucose to insulin ratios were unaffected. Total cholesterol decreased from 6.3 to 6.2 mmol/L (p < 0.005), high-density lipoprotein cholesterol from 1.13 to 1.10 mmol/L (p < 0.048) and the ratio of n-6 to n-3 fatty acids in phospholipids from 2.5 to 1.9 (p < 0.003). Concentrations of leptin decreased from 12.1 to 9.9 ng/mL (p < 0.005) and adiponectin increased from 8.6 to 10.5 microg/mL (p < 0.024). The effect on leptin was confined to women. A low-fat diet intervention for 3 days in insulin-resistant type 2 diabetes affects lipid, adiponectin and leptin levels but fails to improve insulin sensitivity and metabolic control.