Ethanol with a mixed meal decreases the incretin levels early postprandially and increases postprandial lipemia in type 2 diabetic patients

Increased postprandial lipemia is a risk marker of cardiovascular disease (CVD). While moderate alcohol drinking is associated with a reduced risk of CVD in nondiabetic and type 2 diabetic patients, it is also known that alcohol increases postprandial triacylglycerol levels. The incretins, glucose-dependent insulinotropic polypeptide (GIF) and glucagon-like peptide 1 (GLP-1), are important hormones from the gut that enhance nutrient-stimulated insulin secretion. Their responses to a moderate alcohol dose in type 2 diabetes have not previously been studied. We sought to determine how alcohol influences postprandial lipid and incretin levels in patients with type 2 diabetes when taken in combination with a fat-rich mixed meal. Eleven patients with type 2 diabetes ingested on 3 separate days in random order 3 different meals containing: 100 g butter alone or 100 g butter in combination with 40 g alcohol and 50 g carbohydrate, or 100 g butter and 120 g carbohydrate. The meal with alcohol and 50 g carbohydrate was isocaloric to that of 120 g carbohydrate. Triacylglycerol levels were measured after separation by ultracentrifugation into a chylomicron-rich fraction with Svedberg flotation unit values (Sf) > 1,000, and a chylomicron-poor fraction with Sf < 1,000. Supplementation of a fat-rich mixed meal with alcohol in type 2 diabetic subjects suppressed GLP-1 early in the postprandial phase and increased the late triacylglycerol responses compared with the 2 other meals. In the chylomicron-rich fraction, both triacylglycerol and cholesterol were increased by alcohol. No significant differences in high-density lipoprotein (HDL)-cholesterol levels were seen. Isocaloric amounts of carbohydrate and alcohol suppressed equally the postprandial free fatty acid levels, but carbohydrate increased the postprandial glucose, GIP, and insulin levels the most. Early in the postprandial phase, alcohol suppresses the incretin responses and increases the late postprandial triacylglycerol levels in type 2 diabetic patients. Whether this reflects an alcohol-induced suppression of the incretin response, which adds to the alcohol-induced impairment of triacylglycerol clearance in type 2 diabetic patients, remains to be elucidated.