The twin cycle hypothesis of the etiology of type 2 diabetes. During long-term intake of more calories than are expended each day, any excess carbohydrate must undergo de novo lipogenesis, which particularly promotes fat accumulation in the liver. Because insulin stimulates de novo lipogenesis, individuals with a degree of insulin resistance (determined by family or lifestyle factors) will accumulate liver fat more readily than others because of higher plasma insulin levels. In turn, the increased liver fat will cause relative resistance to insulin suppression of hepatic glucose production. Over many years, a modest increase in fasting plasma glucose level will stimulate increased basal insulin secretion rates to maintain euglycemia. The consequent hyperinsulinemia will further increase the conversion of excess calories to liver fat. A cycle of hyperinsulinemia and blunted suppression of hepatic glucose production becomes established. Fatty liver leads to increased export of VLDL triacylglycerol (85), which will increase fat delivery to all tissues, including the islets. This process is further stimulated by elevated plasma glucose levels (85). Excess fatty acid availability in the pancreatic islet would be expected to impair the acute insulin secretion in response to ingested food, and at a certain level of fatty acid exposure, postprandial hyperglycemia will supervene. The hyperglycemia will further increase insulin secretion rates, with consequent enhancement of hepatic lipogenesis, spinning the liver cycle faster and driving the pancreas cycle. Eventually, the fatty acid and glucose inhibitory effects on the islets reach a trigger level that leads to a relatively sudden onset of clinical diabetes. Figure adapted with permission from Taylor (98).
If your cells aren’t responding to insulin, your pancreas produces more to turn up the volume on the signal that glucose is available and the cells should absorb it. When your pancreas can keep up, blood glucose stays within healthy ranges, and all is well. When your pancreas starts to poop out, you end up with insulin deficiency, which leads to blood sugar fluctuations and weight gain.
For Type 1 diabetics there will always be a need for insulin injections throughout their life. However, both Type 1 and Type 2 diabetics can see dramatic effects on their blood sugars through controlling their diet, and some Type 2 diabetics can fully control the disease by dietary modification. As diabetes can lead to many other complications it is critical to maintain blood sugars as close to normal as possible and diet is the leading factor in this level of control.
But is John “free of diabetes”? This is where the lines become blurred. Medically speaking, the term “cure” is usually associated with acute disease—a temporary medical condition, such as bacterial pneumonia, that can be cured with antibiotics. For diabetes, which is a chronic disease, it may be more accurate to use the term “remission” rather than cure. Particularly when considering the pathology associated with diabetes and the individual’s genetic predisposition, relapse is always possible. In a consensus statement issued by the ADA, the term remission is defined based on the following definitions:2
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
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