Diabetes Care 30:2794-2799, 2007 DOI: 10.2337/dc07-0589 © 2007 by the American Diabetes Association
Pramlintide Improved Glycemic Control and Reduced Weight in Patients With Type 2 Diabetes Using Basal Insulin
1 Division of Endocrinology, Diabetes and Clinical Nutrition, Department of Medicine, Oregon Health and Science University, Portland, Oregon Address correspondence and reprint requests to Orville Kolterman, MD, Amylin Pharmaceuticals, 9360 Towne Centre Dr., San Diego, CA 92121. E-mail: orville.kolterman{at}amylin.com
OBJECTIVE— To assess the efficacy and safety of pramlintide in patients with type 2 diabetes suboptimally controlled with basal insulin.
RESEARCH DESIGN AND METHODS— In a 16-week, double-blind, placebo-controlled study, 212 patients using insulin glargine with or without oral antidiabetes agents (OAs) were randomized to addition of pramlintide (60 or 120 µg b.i.d./t.i.d.) or placebo. Insulin glargine was adjusted to target a fasting plasma glucose concentration of 70–100 mg/dl. One coprimary end point was the change in A1C at week 16. The other coprimary end point was a composite measure of overall diabetes control comprising A1C RESULTS—More pramlintide- than placebo-treated patients achieved the composite end point (25 vs. 7%; P < 0.001). Reductions (means ± SE) in A1C (–0.70 ± 0.11% vs. –0.36 ± 0.08%; P < 0.05) and PPG increments (–24.4 ± 3.6 mg/dl vs. –0.4 ± 3.0 mg/dl; P < 0.0001) were greater in pramlintide- versus placebo-treated patients, respectively. Glycemic improvements were accompanied by progressive weight loss with pramlintide and weight gain with placebo (–1.6 ± 0.3 kg vs. +0.7 ± 0.3 kg; P < 0.0001). No treatment-related severe hypoglycemia occurred. CONCLUSIONS— Pramlintide improved multiple glycemic parameters and reduced weight with no increase in hypoglycemia in patients with type 2 diabetes who were not achieving glycemic targets with basal insulin with or without OAs.
Abbreviations: FPG, fasting plasma glucose OA, oral antidiabetes agent PPG, postprandial glucose
Type 2 diabetes is characterized by insulin resistance and progressive β-cell dysfunction resulting in deficiencies of insulin and amylin. Due to the progressive nature of the disease, therapy for most patients starts with medical nutrition therapy and exercise and is followed by the addition of one or more oral antidiabetes agents (OAs). Insulin, usually a basal, long-acting preparation, is eventually required to achieve adequate glycemic control. While basal insulin therapy can result in adequate fasting glucose control, it does not address postprandial hyperglycemia (1,2). Even with rigorous basal insulin titration, 30–40% of patients do not reach acceptable A1C levels ( 7.0%) (3,4). For those not achieving glycemic targets, intensification of therapy with the addition of mealtime insulin increases the risk of hypoglycemia (5–7) and often results in undesirable weight gain (8–10). Pramlintide is a synthetic analog of human amylin, a naturally occurring neuroendocrine hormone cosecreted with insulin by pancreatic β-cells (11). Amylin regulates gastric emptying (12), suppresses inappropriate postprandial glucagon secretion (13), and reduces food intake (14,15). Through mechanisms similar to those of amylin, pramlintide reduces postprandial glucose (PPG), improving overall glycemic control (16,17), and increases satiety, resulting in reduced food intake and weight loss (16–19). Therapies that improve glycemic control without weight gain and its associated long-term complications and do not increase the risk of severe hypoglycemia will significantly enhance treatment of patients with type 2 diabetes. This study investigated the efficacy and safety of pramlintide therapy with basal insulin titration in patients with type 2 diabetes suboptimally controlled with basal insulin, with or without OAs.
Enrolled patients were aged 25–75 years with type 2 diabetes and not achieving adequate glycemic control with insulin glargine (no mealtime insulin), with or without OA therapy (metformin, sulfonylurea, and/or thiazolidinedione). Inclusion criteria at screening included A1C >7.0% and 10.5%, BMI 25–45 kg/m2, insulin glargine treatment 3 months with a stable dose (±10%) for 1 month, and, if applicable, a stable dose of OAs for 2 months. Female patients were postmenopausal, surgically sterile, or used adequate contraception throughout the study. Patients were excluded if they had a history of hypoglycemia unawareness or recurrent severe hypoglycemia during the preceding 6 months, were participating in a weight loss program, were using antiobesity agents, or had a confirmed diagnosis of gastroparesis or any other significant medical condition. The study protocol was approved by an institutional review board. All patients provided written informed consent before study initiation. The study was conducted in accordance with principles outlined in the Declaration of Helsinki (1964), including all amendments through the South Africa revision (1996).
This was a 16-week, randomized, double-blind, placebo-controlled, multicenter study conducted in the U.S. (41 sites) between October 2005 and June 2006. After a screening visit, eligible patients made six visits to the study site (baseline, 2, 4, 8, 12, and 16 weeks). At the baseline visit, patients were randomized to receive pramlintide (Amylin Pharmaceuticals, San Diego, CA) or placebo (Amylin Pharmaceuticals). Randomization was stratified according to screening visit A1C (
Study medication (pramlintide or placebo) was self-administered subcutaneously immediately before major meals depending on the patient's typical meal pattern (b.i.d. or t.i.d.). Patients initiated study medication at a volume equivalent to 60 µg pramlintide per dose and escalated to a volume equivalent to 120 µg per dose within 3–7 days if no clinically significant nausea occurred. Once the maintenance dose was achieved, investigators were asked to make weekly adjustments in the insulin glargine dose to target a fasting glucose concentration of
Study end points
Statistical analyses
Analyses were performed on patients within the intent-to-treat population, all of whom received at least one dose of study medication. Missing individual data were imputed from the last scheduled visit using the last-observation-carried-forward approach for all efficacy analyses, with the exception of FPG, insulin dose, and the seven-point glucose profiles that were analyzed using the intent-to-treat observed population. Fisher's exact test was used to compare the proportion of patients achieving the coprimary composite and secondary binary end points. A general linear model including treatment, baseline A1C stratum (
Patient disposition and baseline demographics Of 212 patients randomized, 91 (85%) placebo-treated and 87 (83%) pramlintide-treated patients completed the study (Table 1). One patient in the placebo-treated arm withdrew consent before injection of study medication, resulting in an intent-to-treat population of 211 patients. Baseline demographics were well matched between treatment arms (Table 1). Eighty-nine percent used at least one OA, and 50% used two or three OAs. Within the pramlintide-treated population, 98 (93%) patients escalated to the 120-µg dose.
Coprimary end points A1C. A1C values progressively decreased throughout the study. Pramlintide-treated patients achieved a significantly (P < 0.05) greater reduction (means ± SE) from baseline at week 16 (–0.70 ± 0.11%) than placebo-treated patients (–0.36 ± 0.08%), exceeding the noninferiority criterion (upper limit of 95% CI = –0.04%) (Fig. 1A). Mean (±SE) A1C values at week 16 were 7.8 ± 0.1% (pramlintide) and 8.1 ± 0.1% (placebo). The proportion of patients achieving an A1C 7.0 or 6.5% was 23 and 11% with pramlintide and 13 and 4% with placebo, respectively.
Composite end point. At week 16, significantly more pramlintide-treated patients achieved the composite end point than placebo-treated patients (25 vs. 7%; P < 0.001) (Fig. 1B).
Secondary end points
Insulin.
Fasting plasma glucose. Mean (±SE) FPG concentrations at week 16 were 119.5 ± 4.1 mg/dl (pramlintide) and 122.8 ± 4.3 mg/dl (placebo), reflecting an average change from baseline of –28.3 ± 6.8 mg/dl (pramlintide) and –12.0 ± 5.6 mg/dl (placebo). An FPG concentration <100 mg/dl was achieved by 28 of 105 (27%) pramlintide-treated and 33 of 106 (31%) placebo-treated patients at week 16.
PPG increments.
Weight.
Patient stratification according to baseline A1C
Baseline A1C
Baseline A1C >8.5%.
Safety The most common adverse events were mild to moderate nausea (31% pramlintide, 10% placebo) and mild to moderate hypoglycemia (44% pramlintide, 47% placebo). Most nausea occurred within the first week of treatment and decreased over time. Two pramlintide-treated patients withdrew from the study due to mild or moderate nausea. Other adverse events leading to withdrawal were treatment-related pruritis at the injection site (one patient in each treatment arm) and alopecia, which was not considered treatment-related (one patient in the pramlintide arm). One event of severe hypoglycemia occurred in a pramlintide-treated patient who accidentally took a dose of rapid-acting insulin instead of insulin glargine. The investigator deemed this event unrelated to pramlintide treatment.
Patients with suboptimal glycemic control on basal insulin therapy may further improve control by increasing the basal insulin dose and/or adding mealtime insulin, but at the expense of additional weight gain and an increased risk of hypoglycemia (1,10). In addition to their clinical significance, these side effects are disliked by patients and, thus, may deter intensification of insulin therapy. This study demonstrated that the addition of pramlintide with continued basal insulin titration allowed such patients to achieve improved glycemic control and additional metabolic benefits not achieved with insulin titration alone. Pramlintide, as an adjunct to basal insulin, allowed patients to achieve an A1C lower than that achieved with basal insulin titration alone. This was accomplished through pramlintide-dependent reductions in PPG increments coupled with reductions in fasting glucose resulting from basal insulin titration. Moreover, as in prior studies of pramlintide used in combination with mealtime insulin (16,17,19), this treatment regimen resulted in weight loss, while insulin titration alone caused weight gain. The coprimary composite study end point, comprising A1C, PPG, weight, and severe hypoglycemia components, was designed to measure the proportion of patients achieving a highly desirable clinical outcome. Significantly more pramlintide-treated patients achieved this end point (25%) than patients receiving insulin alone (7%), confirming the clinical advantages of pramlintide plus basal insulin over basal insulin alone. Therapies that reduce PPG and body weight may provide long-term benefits to patients with type 2 diabetes. Postprandial hyperglycemia has been implicated in the development of micro- and macrovascular complications through mechanisms including increased oxidative stress and inflammation (20–22). Moreover, obesity is very common in patients with type 2 diabetes and contributes to an already-increased risk of cardiovascular disease.
Whether the severity of A1C elevation at baseline affects the benefits of adding pramlintide is of clinical interest. Therefore, ad hoc analyses were performed on patient subgroups with baseline A1C >8.5 or
This study had several limitations. First, the relatively short 16-week duration was not long enough to allow insulin dosage, A1C, and weight to plateau. Second, many patients entering this study had high A1C values despite substantial basal insulin doses ( Pramlintide added to basal insulin was generally well tolerated. Earlier studies of pramlintide indicated an increased risk of insulin-induced severe hypoglycemia, which occurred primarily in the more hypoglycemia-prone type 1 diabetic population (16,17). In contrast, no treatment-related severe hypoglycemia occurred in the present study. Also, the frequency of mild-to-moderate hypoglycemia was similar between the two treatment arms, despite the fact that pramlintide-treated patients achieved significantly better glycemic control. In summary, adding pramlintide to basal insulin improved multiple aspects of diabetes control, thereby addressing important challenges associated with intensifying insulin therapy. These findings support pramlintide as a potential option for the next therapeutic step when patients with type 2 diabetes are not achieving glycemic targets with basal insulin therapy. Further studies examining pramlintide as an alternative to mealtime insulin are warranted.
Participating investigators: A. Ahmann, S. Aronoff, R. Bhushan, W. Cheatham, R. Cherlin, G. Collins, M. Feinglos, N. Fishman, G. Grunberger, R. Guthrie, P. Hollander, R. Kaplan, D. Karl, A. King, E. Klein, L. Levinson, P. Levy, M. May, M. Magee, A. McCall, W. Miers, T. Moretto, L. Olansky, W. Petit, A. Philis-Tsimikas, S. Plevin, J. Pullman, B. Ramlo-Halsted, M. Rendell, M. Riddle, D. Robertson, R. Rood, J. Rosenstock, J. Shapiro, T. Wahl, R. Weinstein, F. Whitehouse, K. Williams, A. Wynne, C. Wysham, and L. Zemel.
Data from this study were presented at the 67th annual meeting of the American Diabetes Association, Chicago, Illinois, 22–26 June 2007, and at the 43rd annual meeting of the European Association for the Study of Diabetes, Amsterdam, the Netherlands, 17–21 September 2007.
Published ahead of print at http://care.diabetesjournals.org on 13 August 2007. DOI: 10.2337/dc07-0589. Clinical trial reg. no. NCT00240253, clinicaltrials.gov. M.R. has received grant/research support from Amylin Pharmaceuticals, Eli Lilly, and sanofi-aventis; has received consulting fees from Amylin Pharmaceuticals, ConjuChem, Emisphere, Eli Lilly, and sanofi-aventis; and has received honoraria from Amylin Pharmaceuticals, Eli Lilly, GlaxoSmithKline, Pfizer, and sanofi-aventis. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C Section 1734 solely to indicate this fact. Received for publication March 25, 2007. Accepted for publication August 3, 2007.
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