Chronic exposure of β-cells to triacylglycerol or fatty acids either in vitro or in vivo decreases β-cell capacity to respond to an acute increase in glucose levels (57,58). This concept is far from new (59,60), but the observations of what happens during reversal of diabetes provide a new perspective. β-Cells avidly import fatty acids through the CD36 transporter (24,61) and respond to increased fatty acid supply by storing the excess as triacylglycerol (62). The cellular process of insulin secretion in response to an increase in glucose supply depends on ATP generation by glucose oxidation. However, in the context of an oversupply of fatty acids, such chronic nutrient surfeit prevents further increases in ATP production. Increased fatty acid availability inhibits both pyruvate cycling, which is normally increased during an acute increase in glucose availability, and pyruvate dehydrogenase activity, the major rate-limiting enzyme of glucose oxidation (63). Fatty acids have been shown to inhibit β-cell proliferation in vitro by induction of the cell cycle inhibitors p16 and p18, and this effect is magnified by increased glucose concentration (64). This antiproliferative effect is specifically prevented by small interfering RNA knockdown of the inhibitors. In the Zucker diabetic fatty rat, a genetic model of spontaneous type 2 diabetes, the onset of hyperglycemia is preceded by a rapid increase in pancreatic fat (58). It is particularly noteworthy that the onset of diabetes in this genetic model is completely preventable by restriction of food intake (65), illustrating the interaction between genetic susceptibility and environmental factors.
Magnesium deficiency is common in diabetic patients, as magnesium can be lost in the urine with hyperglycemia. A study in Diabetes Care reported that low magnesium status is common in Type 2 Diabetes Mellitus (T2DM) and showed that when low-magnesium Type 2 Diabetes Mellitus patients were given an oral dose of magnesium daily for sixteen weeks, the mineral reduced insulin resistance, fasting glucose, and A1C levels.
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.