Effects of rosuvastatin and atorvastatin on glycaemic control in Type 2 diabetes---the CORALL study

To examine whether high-dose statin therapy in Dutch European patients with Type 2 diabetes and dyslipidaemia influenced variables of glycaemic control.

The CORALL study, which was a 24-week, open-label, randomized, parallel-group, phase IIIb, multi-centre study, was designed to compare the cholesterol-lowering effects of rosuvastatin compared with atorvastatin in patients with Type 2 diabetes. Fasting plasma glucose levels and HbA(1c) levels were collected at baseline and at 6 and 18 weeks.

Treatment with the highest dose of statins, i.e. atorvastatin 80 mg and rosuvastatin 40 mg at 18 weeks from baseline, was associated with increase in HbA(1c) levels; baseline 57 ± 11 mmol/l (7.4 ± 1.0%) to 61 ± 14 mmol/mol (7.7 ± 1.3%) (range 5.0-11.9) for atorvastatin (P = 0.003) and from baseline 60 ± 11 mmol/mol (7.6 ± 1.0%) to 63 ± 13 mmol/mol (7.9 ± 1.2%) (range 5.7-12.3) for rosuvastatin (P < 0.001). Mean fasting plasma glucose increased from baseline 8.7 ± 2.4 mmol/l to 9.5 ± 3.0 mmol/l upon treatment with atorvastatin 20 mg (P = 0.002) and 9.0 ± 3.0 mmol/l after treatment with 80 mg (not significant compared with baseline). The mean fasting plasma glucose did not change after treatment with rosuvastatin (9.1 ± 2.7 mmol/l at baseline, 8.9 ± 2.7 mmol/l with 10 mg, 9.4 ± 2.9 mmol/l with 40 mg).

Glycaemic control deteriorated in patients with diabetes following high-dose statin therapy. Future controlled studies are needed to verify these findings and, if confirmed, determine whether such changes represent a true decline in glycaemic control. Presently, it appears that, based on the overwhelming prospective trial data available, the preventive effect of statin therapy supersedes that of the slight increase in HbA(1c).