Relationships between serum lipids, platelet membrane fatty acid composition and platelet aggregation in type 2 diabetes mellitus.

In order to gain further insight into the mechanism of platelet dysfunction frequently reported in diabetes we investigated circulating fatty acids, lipid composition of platelet membrane and platelet function in Type 2 diabetic patients. In these subjects, percentages of C16 : 1n-7 and C18 : 1n-9 in serum phospholipid fraction and of C16 : 1n-7 in serum cholesterol ester fraction were decreased. Moreover, the content of C20 : 4n-6 in serum cholesterol esters was altered in Type 2 diabetic subjects: C18 : 0 and C20 : 3n-6 were increased but C20 : 4n-6 content was similar to controls. Aggregation in vitro did not differ from controls but aggregation in vivo was increased in Type 2 diabetic subjects. No correlation was observed between metabolic parameters -i.e., HbA1, blood glucose, serum triglycerides and total cholesterol, circulating fatty acids and fatty acid content of platelet membrane. A negative linear correlation was found between aggregation in vivo and C20 : 4n-6 content of platelet membrane. Moreover, a U shaped relationship was observed between platelet aggregation in vitro and C20 : 4n-6 content of platelet membrane suggesting that C20 : 4n-6 level should be tightly controlled otherwise platelet hyperreactivity may occur. These results indicate that despite a normal mean C20 : 4n-6 content in the platelet membrane, regulation of C20 : 4n-6 metabolism is less strictly controlled in Type 2 diabetes mellitus and confirm the importance of arachidonic acid platelet content in the regulation of platelet aggregability.