'Healthy living' and sulphonylurea therapy have different effects on glucose tolerance and risk factors for vascular disease in subjects with impaired glucose tolerance

Abstract

This study was undertaken to determine whether impaired glucose tolerance and associated risk factors for cardiovascular disease can be improved with 'healthy living' by diet and exercise or with sulphonylurea therapy. Patients were recruited by screening subjects with either a family history of type II diabetes, previous gestational diabetes, or a previously raised plasma glucose (5.6-6.6 mmol/l). Impaired glucose tolerance was defined as hyperglycaemia on two separate tests, an achieved glucose level after a glucose infusion test above the 90th percentile of an age-matched normal population (> 9.3 mmol/l) or a fasting plasma glucose above the 95th percentile (> 5.6 mmol/l). Thirty-seven subjects with impaired glucose tolerance were entered into a randomized, prospective study for 6 months with allocations to healthy living or double blind to sulphonylurea (gliclazide 40 mg twice daily) or placebo tablets. The study took place in an out-patient setting, with three times weekly exercise sessions at a Sports Centre. After 6 months the placebo group showed no change in plasma glucose, cholesterol and blood pressure. The subjects receiving gliclazide showed improved glucose levels (mean fasting plasma glucose levels fell from 5.8 to 5.1 mmol/l, p < 0.05) but no significant change in plasma cholesterol or blood pressure. The healthy living group, after exclusion of four non-compliant subjects, showed no change in glucose levels, but a decreased systolic blood pressure (fall in mean from 124 to 116 mmHg, p < 0.05) and plasma cholesterol levels (fall in mean from 5.2 to 4.5 mmol/l, p < 0.01). with an increase in HDL:LDL ratio (rise in mean from 0.39 to 0.46, p < 0.05). Subjects with impaired glucose tolerance may benefit in different ways from gliclazide and healthy living. The metabolic responses to each therapy may help to decrease the risk of developing diabetes and cardiovascular disease.