OBJECTIVE--To examine the association of seal oil and salmon consumption with impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) among Alaska Natives. RESEARCH DESIGN AND METHODS--Screening was performed on 666 Yup'ik Eskimos and Athabaskan Indians > or = 40 years old in 15 villages. Self-administered questionnaires were used to obtain partial food frequency data. A case was defined as IGT or NIDDM, either newly discovered or known. Newly discovered cases (11 patients with NIDDM and 17 with IGT) were determined by random blood glucose testing followed by a 2-h 75-g oral glucose tolerance test (OGTT) for those with values > or = 6.72 mmol/l or for subjects with unconfirmed histories of glucose intolerance. Known cases included 26 patients with NIDDM and 1 with IGT. Control subjects had random blood glucoses