A recent study has found that high post-meal insulin surges could indicate positive metabolic health, challenging the traditional belief that they are harmful. The research, focused on the long-term cardiometabolic consequences in new mothers, revealed that higher corrected insulin response (CIR) levels are linked to improved beta-cell function and a reduced risk of developing pre-diabetes or diabetes. This study has the potential to reshape the understanding of insulin’s role in metabolism and weight management. It challenges the concept that an insulin spike after eating is detrimental. Scientists at Sinai Health have gained crucial insights into the connection between post-meal insulin levels and long-term cardiac and metabolic well-being. This research challenges the prevailing belief that an insulin spike after eating is a bad thing and indicates that it may actually be a sign of future good health. The study, led by Dr. Ravi Retnakaran, a Clinician-Scientist at the Lunenfeld-Tanenbaum Research Institute, part of Sinai Health, aimed to investigate how insulin levels after meals impact cardiometabolic health. Whereas previous research has generated conflicting results, suggesting both harmful and beneficial effects, this new study sought to provide a clearer picture over an extended period of time. The team published their findings in the online journal eClinicalMedicine, which is part of the Lancet group. Understanding the Role of Insulin Ordinarily, insulin levels increase after eating to facilitate blood sugar management. However, there is concern over whether a rapid increase in insulin following a meal could be indicative of poor health. Some believe that the insulin surge, particularly after consuming carbohydrates, leads to weight gain and contributes to insulin resistance, where the body’s cells respond poorly to insulin, making it challenging to control blood sugar levels and increasing the risk of type 2 diabetes. Dr. Retnakaran, who is an Endocrinologist at the Leadership Sinai Centre for Diabetes at Mount Sinai Hospital and holds the Boehringer Ingelheim Chair in Beta-cell Preservation, Function, and Regeneration, addressed this notion. He noted that some of his patients have adopted the idea that their insulin levels should not rise too high, possibly influenced by information they encountered online or in their readings. However, he emphasized that the scientific evidence is insufficient to support this viewpoint. Most studies on this topic were either conducted over a short period or were based on inadequate and potentially misleading isolated insulin measurements. Methodology and Participants To address this issue, Dr. Retnakaran’s team examined the cardiometabolic implications of insulin response over the long term, while accounting for baseline blood sugar levels. This aspect is crucial because each individual has a unique insulin response that varies based on their blood sugar levels. The study focused on new mothers because the insulin resistance that occurs during pregnancy provides insight into their future risk of type 2 diabetes. The researchers recruited 306 participants during pregnancy, between 2003 and 2014, and conducted comprehensive cardiometabolic testing, including glucose challenge tests, at one, three, and five years after giving birth. The glucose challenge test measures glucose and insulin levels at various time points following the consumption of a sugary drink containing 75 grams of glucose, after a period of fasting. Implications and Future Directions Although the interpretation of insulin levels from the test is commonly used in medical practice, it can be misleading if baseline blood sugar is not taken into account. Dr. Retnakaran explained that it is not just about insulin levels, but also about understanding them in relation to glucose, a factor that was often overlooked in past interpretations. He highlighted the significance of the corrected insulin response (CIR), which considers baseline blood glucose levels and is gradually gaining prominence in the field. The study revealed unexpected trends, showing that as the corrected insulin response increased, there was a noticeable deterioration in waist circumference, HDL (good cholesterol) levels, inflammation, and insulin resistance. However, these seemingly negative trends were accompanied by improved beta-cell function. Beta cells produce insulin, and their ability to do so is closely associated with diabetes risk. Dr. Retnakaran emphasized that their findings did not support the carbohydrate-insulin model of obesity, and that a robust post-challenge insulin secretory response, adjusted for glucose levels, is only associated with beneficial metabolic effects. In the long run, higher corrected insulin response levels were linked with improved beta-cell function and lower glucose levels, without a correlation with BMI, waist size, lipids, inflammation, or insulin sensitivity or resistance. Most importantly, women with the highest CIR had a significantly reduced risk of developing pre-diabetes or diabetes in the future. The study was funded by the Canadian Institutes of Health Research.
Reference: “Future cardiometabolic implications of insulin hypersecretion in response to oral glucose: a prospective cohort study” by Ravi Retnakaran, Jiajie Pu, Anthony J. Hanley, Philip W. Connelly, Mathew Sermer and Bernard Zinman, 13 December 2023, eClinicalMedicine.
DOI: 10.1016/j.eclinm.2023.102363
