Glucose tolerance and insulin-resistance syndrome among St. Lawrence Island Eskimos

Abstract

Objectives: Non-insulin-dependent diabetes mellitus (NIDDM) prevalence in Alaska Natives is rising but remains lower than the U.S. average. We conducted a screening study for diabetes mellitus and cardiovascular disease in a remote Yup'ik Eskimo community in Alaska.

Research design and methods: The study population included Siberian Yup'ik Eskimo residents of Gambell, Alaska, > or = age 40 years who underwent a 2 h 75 gm oral glucose tolerance test interpreted by WHO criteria. Other measurements included fasting serum insulin and lipid levels, bioimpedance body fat %, body-mass-index (BMI), waist-to-hip ratio (WHR), and blood pressure.

Results: Of 114 eligible subjects, 65 (57%) participated. These subjects had lower mean systolic or diastolic blood pressure, lower triglyceride, and higher mean HDL cholesterol levels compared to a similarly aged U.S. all races sample. The mean fasting insulin level of 50.9 pmol/L appeared low given the high mean BMI (27.2). Six subjects had NIDDM (9%, 95% CI 2%-16%) and eight had impaired glucose tolerance (IGT) (12%, 95% CI 4%-20%). Compared to normoglycemic subjects, diabetic subjects were more frequently female (83% vs 53%) and had higher mean systolic BP (138 mm Hg vs 117 mm Hg) than normoglycemic subjects. We used multiple regression to analyze associations between fasting insulin and either blood pressure or serum lipids, while adjusting for % body fat, WHR, age, sex, and antihypertensive medication use. Fasting insulin was significantly related to both diastolic blood pressure (p = .0430) and fasting serum triglyceride (p = .0182) but not to systolic BP, total cholesterol, or LDL and HDL subfractions.

Conclusions: Although NIDDM prevalence was not high compared to non-Native U.S. residents, elements of the insulin-resistance syndrome exist in this subarctic population.