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

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.

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.

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 μU 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.

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.