Insulin Resistance: What are the causes?
Many factors contribute to insulin resistance from genetic defects in insulin receptor function to dietary issues like low omega-3 intakes or high fructose consumption, to ageing, obesity, central adiposity and consequent abnormal fat hormone (adipokine) signalling, to sedentary lifestyles and loss of lean muscle mass (sarcopenia).
Irrespective of the cause, insulin resistance will over time lead to higher and higher glucose and triglyceride levels in the blood especially after eating (Postprandial effects).
Your overall long term risk is cardiovascular disease and stroke is a common complication of diabetes which is often the end result of prediabetes.
Prediabetes is dealt with poorly by the medical profession and not because it is not important but because of the sheer scale of the disease that affects close to 4 million people in Australia and around 86 million people in the USA. If you were in power in the government and had the ability to add 4 million people to free Medicare services would you? The sheer number of people with this problem if added as a disease state to be compensated for by governmental resources would add a great burden to the cost of Medicare and as such this is a very neglected area of medicine that will kill millions over time. It is up to you to research this disease state and take matters in your own hands. What follows is the mechanism and metabolic consequences of the insulin resistant state.
Normal insulin signalling
When you eat food, both glucose and protein will promote insulin release from the pancreas. We will look at carbohydrate intake in particular. After eating a carbohydrate-based meal (pasta, rice, potatoes, bread, soft drinks (sodas), sweets, pastries, grains), the carbohydrate will be broken down into glucose and this will be absorbed into your blood stream creating a glucose surge that will linger on for many hours. With normal insulin signalling, insulin attaches to the insulin receptor and through a chemical signal, instructs the glucose receptor (the GLUT4), to open the ‘gates’ and allow glucose to flow into the cell for energy production or other metabolic purposes. This animation shows this process in action.
Insulin Resistance in Action
As I have stated above, the insulin receptor may have many defects due to genetics, age, signalling problems, cell membrane issues such as decreased membrane fluidity due to a high saturated fat intake and a suboptimal omega-3 fatty acid intake. Irrespective of the cause, this means that the insulin receptor does not allow insulin to attach and function normally. This means that the signal to the glucose receptor will be severely impaired or blocked.
Insulin Resistance in Action: Rising insulin and glucose levels
Due to the fundamental problem with the insulin receptor being unresponsive to insulin secreted by the pancreas, the feedback the pancreas is getting is that there is a buildup of glucose in the blood and that it needs to produce more insulin to allow glucose to enter the cells for metabolism. The pancreas pours out insulin to try and overcome an obstacle just like a surge of troops is sent to a battle zone to do the same. What you are left with is ever-increasing amounts of insulin in the bloodstream followed by ever increasing glucose. The glucose is toxic to tissues and organs and this results in a buildup of plaque in the coronary (heart) arteries, in blood vessels of the brain and limbs and the carotid arteries leading to the brain. The high glucose leads to cataract formation in the eyes and to kidney failure. It is high-risk for a heart attack and stroke.
This is a the end result of not controlling the insulin resistant state. There is a slow and inexorable progression to diabetes in the vast number of people with insulin resistance (prediabetes) and by the time diabetes has been discovered, 80% of beta cell mass has been lost! Your only hope now is the use of injected insulin with its inherent problems. Preventing beta-cell burnout is a far more clever option through strict diet, exercise, weight loss where necessary and resistance training to improve muscle mass and in doing so, active muscle tissue helps improve blood glucose levels
Can you prevent diabetes if you have prediabetes or early insulin resistance?
That the prediabetic state can be reversed and that diabetes can be prevented, is something that every doctor should now know as this is an evidence-based fact from a very long running study called the DPPOS outcomes study (below). This prediabetes/insulin resistance diagnosis is extremely underrated and General Practitioners (GPs) just don’t look for this extremely serious problem and if they find it, don’t know what to do with it or are confused about the long-term benefits of treating this disease because in many a GP’s mind, you can’t halt the progression of the prediabetic state to diabetes – how wrong this way of thinking is!
Your risk of cardiovascular disease (heart attack, erectile dysfunction (ED), peripheral vascular disease where blood vessels in your legs and elsewhere become blocked, and your risk of stroke is very high and almost the same as someone who has established diabetes. The 15-year Diabetes Prevention Program Outcomes Study (DPPOS) funded by the National Institutes of Health (NIH) in the USA has shown a 58% reduction in risk of developing diabetes with lifestyle modification and with the use of Metformin, a 31% reduction in this risk. Metformin is extremely underused. It is safe and has tremendous benefits and is now an evidence-based way of decreasing the risk of prediabetes progressing to diabetes by a massive 1/3. How much will this save strugging Western societies by decreasing the cost of medical care through diabetes prevention by a safe and very cheap medication? To not discuss intensive lifestyle modification and the use of Metformin in prediabetic/insulin resistant states is in my mind unconscionable and indeed unethical given the tremendous damage caused by these prediabetic metabolic states.
We know that anyone who undergoes bariatric surgery such as banding or surgery to decrease the capacity of the stomach to hold food, that within 4 days there are dramatic changes in blood risk factors such as blood glucose levels or blood fat levels and that some can reverse their diabetes after surgery. That this cannot be taken back to normal in a large number of people is an absolute myth believed by many individuals and doctors alike.
Without strict dietary management and a guided exercise routine, you risk serious disease and a much shorter lifespan.