Efficacy of conversion from bedtime NPH insulin to morning insulin glargine in type 2 diabetic patients on basal-prandial insulin therapy

In normal subjects, approximately half of the daily insulin requirement constitutes basal insulin. We investigated whether increasing the dose of insulin glargine up to half of the total insulin requirement could lead to better glycemic control in type 2 diabetic patients who were treated on basal-prandial insulin therapy. A total of 62 patients with type 2 diabetes on mealtime rapid-acting insulin analogue and bedtime NPH were randomized to either continuation of bedtime NPH (n = 31) or morning glargine (n = 31) for 6 months while continuing the aspart/lispro at each meal. The two groups were matched for age, sex, diabetes duration, BMI, HbA1C, endogenous insulin secretion, and proportion of numbers using aspart/lispro and using oral hypoglycemic agents. The dose of insulin glargine was increased by 2–4 units to meet the target fasting blood glucose, whereas the dose of NPH was principally unchanged as a control group. Mean HbA1C at baseline was similar between patients with glargine and NPH (7.2% versus 6.9%). The percentage of glargine dose increased significantly (31% at baseline to 48% at 6 months) without any significant changes in total insulin dose. Mean HbA1C at 3 months was 6.6% with glargine and 7.0% with NPH (P < 0.0001, adjusted mean change between-treatment difference 0.6% [95% CI 0.3–0.9]), and the values at 6 months were 6.6% and 6.9%, respectively (P = 0.007). Frequency of hypoglycemia did not differ between the groups. Increasing the dose of glargine without changing the total daily insulin dose resulted in significantly better glycemic control in type 2 diabetic patients on basal-prandial insulin therapy. Conversion from bedtime NPH to morning glargine appears efficacious with no increase in frequency of hypoglycemia.