Trends in Hyperinsulinemia Among U.S. Adults without Diabetes: A Joinpoint Analysis

Hyperinsulinemia is associated with various chronic diseases and cardiovascular disease risk factors. Investigating changes in hyperinsulinemia over time is important due to its association with pervasive clinical outcomes. PURPOSE: Estimate the prevalence and examine trends in hyperinsulinemia among euglycemic U.S. adults between 1999 and 2018. METHODS: Weighted data from adults ≥20 years of age from the 1999-2018 cycles of the National Health and Nutrition Examination Survey (NHANES) were analyzed. Exclusion criteria included pregnancy, history of diabetes or blood glucose ≥126 mg/dL, and taking diabetes medications (n=23,447). The 20-year trend for hyperinsulinemia (defined as the 75th percentile of log-transformed insulin) was nonlinear. The 2009-2010 cycle was identified as a joinpoint, creating two segments – 1999/2000 to 2009/2010 and 2009/2010 to 2017/2018. Each segment was examined for significant trends. RESULTS: Overall, an initial rise in hyperinsulinemia was followed by a drop and plateau. The age-adjusted prevalence of hyperinsulinemia increased by ~18% in the study population between 1999/2000 and 2017/2018 (21.5% to 25.3%, P for trend 0.0034). The age-adjusted prevalence of hyperinsulinemia increased by ~65% in the first joinpoint segment (21.5% to 35.4%, P for trend <0.0001). The prevalence of hyperinsulinemia decreased ~29% in the second joinpoint segment, but not significantly (35.4% to 25.3%, P for trend=0.10). CONCLUSION: Hyperinsulinemia rates in U.S. adults without diabetes significantly increased at the turn of the century, however, the more recent decline and steadying of rates may be due to improved medication regimens and lifestyle modifications. Both warrant further investigation in this population.