Gestational diabetes: emerging concepts in pathophysiology.

Gestational diabetes affects 3 to 5% of pregnancies in the United Kingdom, contributing to significant maternal and fetal morbidity. Understanding the pathophysiology is important as it guides diagnostic screening and treatment. The insulin resistance of normal pregnancy facilitates provision of metabolic substrates to the fetus and is multifactorial in origin. Recent identification of hepatic and skeletal muscle lipid deposition in Type 2 diabetics, demonstrated by novel magnetic resonance spectroscopy techniques, is likely to be the underlying cause of pathological insulin resistance. Similar mechanisms almost certainly underlie gestational diabetes, although further studies are required to prove this. Women who develop gestational diabetes have demonstrable insulin resistance prior to pregnancy that is part of a chronic process of lipid accumulation ultimately leading to type 2 diabetes later in life. The importance of lifestyle advice and dietary modification and the rationale behind the use of metformin are thus explained.