Reduced weight gain with insulin detemir compared to NPH insulin is not explained by a reduction in hypoglycemia.

Background: Weight gain often occurs when insulin therapy is initiated. The long-acting insulin analog insulin detemir has been shown to be effective and well tolerated when used in basal-bolus regimens or as an add-on to oral antidiabetic drugs (OADs) and causes less weight gain than other insulins. The aim of this exploratory analysis was to investigate any correlations between weight change and occurrence of hypoglycemia with NPH insulin and insulin detemir.

Methods: The analysis was based on a 26-week, randomized, multicenter, open-label, parallel-group trial in which glycemic control, hypoglycemia, and weight change were compared between insulin detemir and NPH insulin. A total of 476 insulin-naive patients with type 2 diabetes treated with one or two OADs added insulin detemir (n=237) or NPH insulin (n=239) morning and evening to their current oral treatment. Weight gain data from this study were analyzed as a function of hypoglycemia frequency.

Results: Both groups achieved excellent glycosylated hemoglobin control (insulin detemir, 6.6%; NPH insulin, 6.5% [difference not significant]). Weight gain with insulin detemir was less than half that of NPH insulin (1.2 vs. 2.8 kg, respectively [P<0.001]), and the overall risk of hypoglycemia was 47% lower with insulin detemir (P<0.001). No significant relationship between hypoglycemia and weight gain was seen with insulin detemir (P=0.2), while a statistically significant correlation was found for NPH insulin (P=0.003).

Conclusions: Hypoglycemia is predictive of weight gain with NPH insulin, but the same relationship is not seen with insulin detemir. It is therefore likely that the weight-sparing effect of insulin detemir involves other mechanisms.