A measure of insulin response to food, developed to capture what the glycemic index misses.
What the evidence says
- The insulin index was developed by Susanna Holt and colleagues at the University of Sydney[1]
- Measures insulin response directly rather than inferring it from blood sugar[1]
- Uses isoenergetic 1000-kJ (240-kcal) portions of food for standardized comparison; 38 foods across 6 categories tested on groups of 11–13 healthy subjects[1]
- Glycemic and insulin scores were highly correlated (r = 0.70) but not identical — some foods that barely raise blood sugar still trigger significant insulin release[1]
- Protein-rich foods stimulate significant insulin despite low/no carbohydrate content[1]
- Dairy products score higher on the insulin index than their carbohydrate content predicts — yogurt scored GS 62 but IS 115, nearly 2× the insulin its blood sugar response would predict[1],[2]
- Bakery products trigger disproportionately high insulin relative to glycemic response[1]
- *The same paper's across-food correlations point the other way, and both facts are its own. Across the food set, total carbohydrate (r = 0.39, P < 0.05, n = 36) and sugar (r = 0.36, P < 0.05, n = 36) contents were positively related to mean insulin scores, while fat (r = −0.27, NS, n = 36) and protein (r = −0.24, NS, n = 38) were negatively related — both non-significant. Note the scopes: this is nutrient content correlated across the tested foods — n = 36 for carbohydrate, sugar and fat, n = 38 for protein, against a set of 38 — whereas the disproportionate-insulin finding above is about particular foods measured against their own glycemic response.* Different questions, so the two do not contradict[1]