What if insulin spikes after a meal were good for your health?

What if insulin spikes after a meal weren't a red alert for the body? For several years, advice on nutrition, but also the prevention of obesity and diabetes, suggested that it's necessary at all costs to get rid of peaks in blood sugar, and therefore insulin, which would promote weight gain and increase the risk of type 2 diabetes, according to several studies. According to these, a patient should start by eating vegetables, avoid consuming too many foods with a high glycemic index, or go for a walk after dinner. It’s good advice to follow to stay healthy generally, but is the reward worth the effort for insulin control?Researchers from the Sinai Health Research Institute and the University of Toronto looked at the relationship between insulin levels and long-term heart and metabolic health, in a study led by Dr. Ravi Retnakaran, associate professor in the Division of Endocrinology and Metabolism at the University of Toronto, and published in the Lancet's online journal, eClinicalMedicine. According to their observations, postprandial hyperinsulinemia could well be an indicator of good health. A disavowal of the “carbohydrate-insulin model of obesity”This is the first time a study on this subject has covered such a long period. Between 2003 and 2014, scientists followed more than 300 women during and after pregnancy, “exhibiting the full range of antepartum glucose tolerance.” They measured their baseline blood sugar levels, glucose tolerance using oral tests and glucose challenge tests—which measure glucose levels at different times after consuming a sugary drink following a period of fasting—but also their sensitivity or resistance to insulin (insulin resistance that occurs during pregnancy can determine the risks of developing type 2 diabetes) as well as cardiovascular risk factors. Testing continued for four years after delivery. “It’s not just about insulin levels; it’s about understanding them in relation to glucose,” explains Dr. Retnakaran in a story from the University of Toronto.If the researchers found a notable increase in waist circumference over year one, “without significant difference in BMI, physical activity or duration of breastfeeding,” levels of good cholesterol (HDL), inflammation and insulin resistance as corrected insulin response (CIR) were also increased. Researchers also discovered better functioning of beta cells, whose insulin-producing capacity is closely associated with the risk of diabetes. The better they work, the lower the risk.Read: QUIZ: Diabetes-related foot infections“Our results do not support the carbohydrate-insulin model of obesity,” explained Dr. Retnakaran. “We observed that a robust insulin secretory response after challenge—once adjusted for glucose levels—is only associated with beneficial metabolic effects.”New perspectives in weight managementHigh insulin levels are thus associated with lower glucose levels and better beta cell function, without correlation with BMI, waist circumference, inflammation or insulin resistance. Women with the highest CIR additionally had a significantly reduced risk of developing prediabetes or diabetes. “A robust secretory insulin response after challenge does not indicate unfavourable cardiometabolic health but rather portends favourable metabolic function in years to come,” the study concluded, stating that the results allow us to better understand the role of insulin in the regulation of metabolism and weight management.So why have so many studies pointed out the harmful nature of insulin peaks after meals? Searching the scientific literature published on the subject between 1950 and 2023, the scientists noted, “There is inconsistent consideration of ambient blood glucose, cross-sectional analyses, and a relative lack of longitudinal studies in which the future cardiometabolic implications of glucose-corrected post-challenge insulinemia were evaluated.”Read: Busting six myths about nutrition

What if insulin spikes after a meal were good for your health?

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