Relative Fasting Hypoinsulinaemia and Ultrasonically Measured Early Arterial Disease in Type 2 Diabetes

Macrovascular disease is the most important cause of morbidity and mortality in Type 2 (non-insulin-dependent) diabetes. Dyslipidaemia and hyperinsulinaemia have been proposed as aetiological factors. This paper describes the interrelationships between fasting serum insulin, serum lipids, and the extent of ultrasonically measured early arterial disease in Type 2 diabetic subjects screened for entry into a prospective study set up to ascertain whether improving serum lipids can alter the progress of arterial disease in Type 2 diabetes. Measurements were made of the initima media thickness (IMT) in the carotid artery, and an arterial ultrasound score (AUS) based on appearances of both carotid and femoral arteries was calculated for 192 established Type 2 diabetic subjects, males and females, mean age 51 (range 35–66) years, median duration of diabetes 3.5 years, with no known cardiovascular disease. Multiple regression analysis showed that carotid IMT increased with age and was inversely related to serum insulin (variance accounted for, R2, = 8.8 %, p = 0.0002). AUS increased with age and was related inversely to serum insulin, or to C-peptide when this was substituted in the model. In addition to age and serum insulin, AUS was positively associated with non-HDL cholesterol and negatively with HDL 3 cholesterol (R2 = 26 %, p = 0.0001). Early thickening and damage to the arterial wall in Type 2 diabetes may be related to relative fasting hypoinsulinaemia.