Researchers at UCLA report that type II diabetes can be caused by repeatedly high levels of insulin from exposing the pancreas to too much fat (Diabetes, Nov 18, 2019). Similar results were also reported previously (Molecules, Jun 19, 2018;23(6):E1483; Diabetes, Aug 1995;44(8):863-70; Br J Nutr, Mar 2000;83 Suppl 1:S79-84). This research tells us that insulin-resistant diabetes can come from eating too much fat as well as from too much sugar.
The UCLA study shows that high blood levels of fatty acids caused mice to produce high levels of a protein called Cyclophilin D (CypD), which stimulates the mitochondria of the beta cells of the pancreas to produce insulin. The researchers then used mice that were genetically modified to be unable to produce CypD and they did not produce large amounts of insulin when exposed to high blood levels of fatty acids. Then they isolated human beta pancreatic cells, put them in a culture plate and found that human pancreatic cells also produce large amounts of insulin when exposed to fatty acids.
Why This Research Makes So Much Sense
We have known for more than fifty years that exposing the pancreas to large amounts or sugar, fat or protein causes high rises in blood insulin levels. The function of insulin is to drive sugar, fat, and protein amino acids into cells. You get high blood levels of insulin after you eat only a steak, just as you would if you ate a sugary dessert.
Most of the sugar that you eat is converted to fat. You can store only a very small amount of sugar in your liver and muscles, and after these tissues fill up with stored sugar called glycogen, all additional sugar is converted to a fat called triglycerides. Most people with fasting triglyceride levels above 150 are already diabetic. Then your good HDL cholesterol clears triglycerides from the bloodstream by carrying them to the liver, so your good HDL cholesterol levels drop. Excess triglycerides deposited in the liver cause a fatty liver and a fatty liver cannot accept sugar from the bloodstream, causing the continued high rises in blood sugar that are typical of diabetes.
How High Insulin Levels Increase Risk for Obesity
Most cases of diabetes are caused by excess fat in your liver. Everyone’s blood sugar rises after they eat. If blood sugar rises too high, sugar can stick to the outer membranes of cells throughout your body. To prevent blood sugar from rising too high, your pancreas releases insulin that lowers blood sugar by driving sugar from the bloodstream into the liver. However, if the liver is full of fat, it does not accept sugar from the bloodstream. The fat-filled liver releases sugar into the bloodstream to raise blood sugar levels even higher. The higher your blood sugar rises, the more insulin a healthy pancreas produces. In prediabetes and early diabetes, high insulin levels accompany high blood sugar levels. However, insulin makes you fat by converting all extra calories to fat and fills the liver with even more fat (Curr Obes Rep, 2017; 6(2): 178-186; Diabetes Obes Metab, Nov 2007;9(6):799-812). The extra fat in the liver raises blood sugar and insulin levels even higher to increase the rate of cell damage. High levels of insulin stimulate all cells to overgrow, which increases cancer risk (Diabetes Care, Jul 2012;35(7):1538-1543). Blood insulin levels keep rising higher and higher until the pancreas becomes exhausted and can produce no insulin at all. Then person must take insulin injections just to stay alive.
Up to 70 percent of North American adults will eventually become pre-diabetic or diabetic, which puts them at increased risk for heart attacks, strokes and premature death. Most cases of diabetes are caused by excess fat in the liver. A fatty liver is caused by eating too much food, not just by eating too much sugar; eating too much fat or too much protein will also fill up the liver with fat. I recommend getting a sonogram (sound wave) test of your liver, which will show whether you have excess fat deposited there.
Most cases of insulin-resistant diabetes cannot be cured with drugs, but can be cured by losing excess weight and adopting a healthful lifestyle. If you have a fatty liver, I recommend intermittent fasting or time-restricted eating, even if you are not overweight. I also recommend following an anti-inflammatory diet and lifestyle which includes exercising, avoiding tobacco and alcohol, and keeping vitamin D levels above 20 ng/mL.