While insulin is a potent activator of essential fatty acid metabolism, portal hypoinsulinemia is common in Type 1 diabetes. Fatty acids were determined by high-resolution capillary gas-liquid chromatography in plasma and erythrocyte membrane lipids in diabetic children (n = 40) and in age-matched healthy controls (n = 40). In plasma phospholipids, values of linoleic acid (23.00 [2.35] vs. 18.13 [2.54], % by wt, median [range from the first to the third quartile], P<0.000l) and alpha-linolenic acid (0.12 [0.06] vs. 0.07 [0.07], P<0.05) were significantly higher in diabetic children than in controls. In contrast, values of arachidonic acid (10.73 [2.34] vs. 11.53 [2.50], P<0.05) and docosahexaenoic acid (2.23 [0.63] vs. 2.77 [0.98], P<0.01) were significantly lower in diabetic children than in controls. Reduced availability of long-chain polyunsaturates in diabetic children suggests that an enhanced dietary supply of long-chain polyunsaturates may be beneficial.