Ten-year weight gain is associated with elevated fasting insulin levels and precedes glucose elevation

Background: Numerous studies have examined the relationship between endogenous insulin and weight change with mixed results. This study examined the relationship between fasting insulin levels, insulin resistance (IR), and 10-year weight change by glycaemic stage. Methods: Using data from the US National Health and Nutrition Examination Survey 2011-2014, 3840 participants were divided into 6 groups based on fasting glucose and fasting insulin levels. Fasting insulin concentrations were dichotomized into <25th percentile (normal) and >= 25th percentile (elevated). Ten-year weight change associated with fasting insulin was assessed by glycaemic stage. Results: Average weight change over a 10-year period was higher in individuals with elevated insulin levels compared to the first quartile (1.40 lbs. vs 11.12 lbs, P < .0001). Across all groups, a 1 mu U increase in fasting insulin levels resulted in a 0.52-pound increase in weight (P < .0001). Similarly, an increase in HOMA-IR was associated with increase in weight (1.32 lbs per IR unit, P < .0001). Marginal increases in weight were most pronounced in the normal insulin groups compared to elevated insulin groups and diminished as glycaemic stage progressed. Conclusions: Elevated fasting insulin level was positively associated with weight gain. The impact of fasting insulin and IR on weight gain preceded hyperglycaemia and diminished as glycaemic stage progressed.