The Effect of Exercise on Hepatic Glucose Metabolism

It is known that obesity and/or physical inactivity greatly increase a person's risk of
developing heart disease and other serious health problems. This is partly because diabetes
is associated with inflammation, oxidative stress, and insulin resistance. Diabetes is also
associated with high levels of triglycerides in the blood and tissues such as the liver
(known as fatty liver or steatosis). This elevation of fat in the liver is known to cause
liver insulin resistance and impair the function of the liver and this impairment contributes
to the development of diabetes.

Studies have shown that both aerobic exercise and weight loss have beneficial results on
insulin resistance. However, the cause of this benefit remains unclear. We know that both
aerobic exercise and/or weight loss can improve how muscle responds to insulin. However, it
is also known that aerobic exercise and/or weight loss lowers liver fat content, thereby
making it possible that the liver's response to insulin is also improved by weight loss
and/or exercise training. An improved responsiveness of the liver to insulin could lower
blood sugar levels after a meal and it could also lower morning blood sugar levels. However,
very little is known about how exercise and/or weight loss improves liver function in people
with type 2 diabetes.

Hypothesis 1: Improved hepatic insulin sensitivity, as a result of exercise training will
increase the amount of glucose from an oral load that is taken up by the liver in subjects
with DM.

Hypothesis 2: Increases in hepatic insulin sensitivity as a result of exercise will cause
reductions in EGP during the fasted state, and will improve the suppression of EGP seen in
response to hyperinsulinemia.