Implications for Treatment of the Metabolic Syndrome

Primary outcomes

1. Muscle Microvascular Function

   Time frame: 6 months

   Skeletal muscle microvascular function assessed (Filtrass plethysmographic system) using a passive inductive transducer (Compumedics.dwl, Singen, Germany) and a small pressure step venous congestion protocol. Fluid filtration rate (Jv mL min-1 100 mL-1), measured from the slope of limb volume change in response to each pressure step (10 mmHg steps to 60 mmHg around the thigh) over the last 2 minutes of its application, to allow for completion of vascular filling, and plotted against cuff pressure (Pcuff). The slope of this relationship, at pressures above those giving rise to net filtration, is a measure of Kf, microvascular filtration capacity, a function of exchange surface area and permeability. The CV for Kf measurement was 14.5%.

2. Insulin Sensitivity Index

   Time frame: 6 months

   Insulin sensitivity index was assessed during the final steady state 30 minutes of a high dose hyperinsulinaemic euglycaemic clamp (insulin infusion rate 1.5 mIU/kg/min). During this part of the clamp, insulin was infused at 1.5mIU/kg/min and the glucose concentration was maintained at 5 mmol/L using a dextrose infusion. The whole body insulin mediated glucose disposal rate (M value - mg/kg/min) was estimated from the total amount of glucose infused during the last 30 minutes of the clamp. The mean of four serum insulin concentrations was taken during this 30 minutes to determine the steady state insulin concentration (I value - milliunits/litre). M value/I value defined the insulin sensitivity index.