Impact of diabetes duration on hypoglycaemia in patients with type 2 diabetes treated with insulin glargine or NPH insulin

AIM: To compare the impact of diabetes duration on hypoglycaemia in patients with type 2 diabetes mellitus (T2DM) treated with insulin glargine or NPH insulin. METHODS: A pooled analysis of 24-week patient level data from randomized controlled studies comparing once-daily insulin glargine with once-daily NPH insulin in insulin-naïve adult patients with T2DM was performed, stratifying patients into quartiles by duration of diabetes: <5.8 years; 5.8 to <9.2 years; 9.2 to <14 years and ≥14 years. Daytime and nocturnal hypoglycaemia events were evaluated. RESULTS: Data from 2330 patients in four randomized controlled trials were included in the analysis; 1258 treated with insulin glargine and 1072 with NPH insulin. The rates of daytime hypoglycaemia were similar for insulin glargine and NPH insulin, irrespective of disease duration. Patients with longer T2DM duration treated with glargine experienced greater glycated haemoglobin A1c (HbA1c) reductions. Rates of severe nocturnal hypoglycaemia and nocturnal hypoglycaemia [self-monitored blood glucose < 70 mg/dl (3.89 mmol/l) and < 50 mg/dl (2.78 mmol/l)] were all significantly and positively correlated with the duration of diabetes for patients treated with NPH insulin but not with insulin glargine. Despite improvements in HbA1c, rates of symptomatic nocturnal hypoglycaemia were significantly lower with insulin glargine than with NPH insulin in patients with longer T2DM duration. CONCLUSION: There is a lower risk for nocturnal hypoglycaemia with insulin glargine than with NPH insulin. When considering diabetes duration, insulin glargine (compared to NPH insulin) may be particularly beneficial in patients with a longer duration of T2DM.