Objective: To determine the extent to which intensive dietary intervention can influence glycaemic control and risk factors for cardiovascular disease in patients with type 2 diabetes who are hyperglycaemic despite optimised drug treatment.
Design: Randomised controlled trial.
Setting: Dunedin, New Zealand.
Participants: 93 participants aged less than 70 years with type 2 diabetes and a glycated haemoglobin (HbA(1c)) of more than 7% despite optimised drug treatments plus at least two of overweight or obesity, hypertension, and dyslipidaemia.
Intervention: Intensive individualised dietary advice (according to the nutritional recommendations of the European Association for the Study of Diabetes) for six months; both the intervention and control participants continued with their usual medical surveillance.
Main outcome measures: HbA(1c) was the primary outcome. Secondary outcomes included measures of adiposity, blood pressure, and lipid profile.
Results: After adjustment for age, sex, and baseline measurements, the difference in HbA(1c) between the intervention and control groups at six months (-0.4%, 95% confidence interval -0.7% to -0.1%) was highly statistically significant (P=0.007), as were the decreases in weight (-1.3 kg, -2.4 to -0.1 kg; P=0.032), body mass index (-0.5, -0.9 to -0.1; P=0.026), and waist circumference (-1.6 cm, -2.7 to -0.5 cm; P=0.005). A decrease in saturated fat (-1.9% total energy, -3.3% to -0.6%; P=0.006) and an increase in protein (1.6% total energy, 0.04% to 3.1%; P=0.045) in the intervention group were the most striking differences in nutritional intake between the two groups.
Conclusions: Intensive dietary advice has the potential to appreciably improve glycaemic control and anthropometric measures in patients with type 2 diabetes and unsatisfactory HbA(1c) despite optimised hypoglycaemic drug treatment.
Trial registration: Clinical trials NCT00124553.