Duloxetine was linked with modest changes in glycemia in patients with diabetic peripheral neuropathic pain (DPNP), according to the results of 3 randomized trials. "The clinical trials of duloxetine for DPNP provide a large database to evaluate potential metabolic effects of duloxetine in patients with diabetes. The current study examined pooled data from both short- and long-term studies to assess changes in weight, glycemia, and plasma lipids and to test for relationships between metabolic changes and baseline clinical factors, as well as the analgesic response to duloxetine treatment."
The investigators pooled data from 3 similarly designed clinical trials in which adults with diabetes and DPNP (n = 1024) were randomized to 60 mg duloxetine once daily, 60 mg twice daily, or placebo for 12 weeks. After this phase, 867 subjects were re-randomized to 60 mg of duloxetine twice daily or to routine care for an additional 52 weeks. Outcome measures included mean changes in fasting plasma glucose (FGP), lipids, and weight, and regression and subgroup analyses were used to identify relationships between metabolic measures and demographic, clinical, and electrophysiologic parameters.
Duloxetine treatment was associated with modest increases in FGP at 12 and 52 weeks (0.50 and 0.67 mmol/L, respectively). Although glycated hemoglobin (HbA1C) levels did not increase in placebo-controlled studies, there was a greater increase compared with routine care in long-term studies (0.52% vs 0.19%). Short-term duloxetine treatment was associated with mean weight loss of -1.03 kg (P < .001 vs placebo). However, longer treatment was associated with slight, nonsignificant weight gain in both duloxetine and routine care groups.
There were some between-group differences for some lipid parameters, but these were generally small. Metabolic changes did not appear to affect the improvement in pain severity associated with duloxetine and did not result in any significant changes in nerve conduction.
"Duloxetine treatment was associated with modest changes in glycemia in patients with DPNP," the authors write. "Other metabolic changes were limited and of uncertain significance. These changes did not impact the significant improvement in pain observed with duloxetine treatment."
Study limitations include inadequate design to evaluate the impact of treatment on glycemic control or other metabolic parameters, the routine care group in extension studies included several different treatments of DPNP, and selected study population limiting the generalizability of the findings.
"We hope that the findings reported here will help clinicians make informed decisions regarding the risks and benefits of duloxetine in patients seeking relief from painful diabetic neuropathy," the authors conclude.
Eli Lilly, the maker of duloxetine, supported this study, employs its lead author, and has disclosed having financial relationships with 2 other authors. The costs of publication of this article were defrayed in part by the payment of page charges, mandating that it must therefore be marked "advertisement."
Diabetes Care. Jan. 2007;30:21-26.
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