The Randle cycle is a metabolic process involving the competition of glucose

Glucose

Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...

 and fatty acid

Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...

s for substrates. It is theorized to play a role in explaining type 2 diabetes and insulin resistance

Insulin resistance

Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...

.

The mechanism involves malonyl-CoA

Malonyl-CoA

Malonyl-CoA is a coenzyme A derivative.-Functions:It plays a key role in chain elongation in fatty acid biosynthesis and polyketide biosynthesis....

 and its inhibition of carnitine palmitoyltransferase I (CPT1). Glucose oxidation produces citrate

Citrate

A citrate can refer either to the conjugate base of citric acid, , or to the esters of citric acid. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate.-Other citric acid ions:...

 which can be converted to malonyl-CoA by acetyl-CoA carboxylase

Acetyl-CoA carboxylase

Acetyl-CoA carboxylase is a biotin-dependent enzyme that catalyzes the irreversible carboxylation of acetyl-CoA to produce malonyl-CoA through its two catalytic activities, biotin carboxylase and carboxyltransferase...

 (ACC1 or ACC). Malonyl-CoA then can bind to and inhibit one of several tissue-specific CPT1 isoforms. CPT1 is a transporter of long-chain fatty acids at the outer mitochondrial membrane

Outer mitochondrial membrane

thumb|300px|Mitochondria structure :1) [[Inner membrane]]2) Outer membrane3) [[Crista]]4) [[Matrix |Matrix]]The outer mitochondrial membrane, which encloses the entire organelle, has a protein-to-phospholipid ratio similar to the eukaryotic plasma membrane...

 that regulates the rate-controlling step for fatty acid oxidation. Thus, increased glucose oxidation inhibits fatty acid oxidation via malonyl-CoA, which can then be utilized as a substrate for fatty acid synthesis.

It is named for Philip Randle

Philip Randle

-References:...

, who described it in 1963.