Diabetes Care 31:20-25, 2008 DOI: 10.2337/dc07-1122 © 2008 by the American Diabetes Association
Advancing Insulin Therapy in Type 2 Diabetes Previously Treated With Glargine Plus Oral AgentsPrandial premixed (insulin lispro protamine suspension/lispro) versus basal/bolus (glargine/lispro) therapy
1 Dallas Diabetes and Endocrine Center, Dallas, Texas Address correspondence and reprint requests to Julio Rosenstock, MD, Dallas Diabetes and Endocrine Center at Medical City, Dallas, TX 75230. E-mail: juliorosenstock{at}dallasdiabetes.com
OBJECTIVE—The purpose of this study was to compare two analog insulin therapies (prandial premixed therapy [PPT] versus basal/bolus therapy [BBT]) in type 2 diabetic patients previously treated with insulin glargine ( 30 units/day) plus oral agents, with the aim of demonstrating noninferiority of PPT to BBT. RESEARCH DESIGN AND METHODS—Patients were randomly assigned to PPT (lispro mix 50/50: 50% insulin lispro protamine suspension and 50% lispro; n = 187) t.i.d. with meals or BBT (glargine at bedtime plus mealtime lispro; n = 187) in a 24-week, multicenter, open-label, noninferiority trial. Investigators could replace lispro mix 50/50 with lispro mix 75/25 at the evening meal if the fasting plasma glucose target was unachievable.
RESULTS—Baseline A1C was similar (PPT 8.8%; BBT 8.9%; P = 0.598). At week 24, A1C was lower with BBT (6.78 vs. 6.95%, P = 0.021). A1C was reduced significantly from baseline for both therapies (P < 0.0001). The difference in A1C change from baseline to the end point (BBT minus PPT) was –0.22% (90% CI –0.38 to –0.07). Noninferiority of PPT to BBT was not demonstrated based on the prespecified noninferiority margin of 0.3%. The percentages of patients achieving target A1C <7.0% (PPT versus BBT, respectively) were 54 vs. 69% (P = 0.009) and for target CONCLUSIONS—Although noninferiority of PPT to BBT was not demonstrated, findings for A1C reduction, percentage of patients achieving A1C targets, hypoglycemia, and number of required injections should be considered in the individual decision-making process of advancing insulin replacement to PPT versus BBT in type 2 diabetes.
Abbreviations: BBT, basal/bolus therapy FPG, fasting plasma glucose OHA, oral antihyperglycemic agent PPT, prandial premixed therapy SAE, severe adverse event SMPG, self-monitored plasma glucose TDI, total daily insulin
The progressive deterioration of pancreatic β-cell function in type 2 diabetes necessitates the advancement of treatment over time for most patients (1,2). For patients in whom treatment with oral antihyperglycemic agents (OHAs) has failed, basal insulin is often initiated (3–10). When glycemic control can no longer be achieved or maintained with this therapy, then prandial insulin is added (11). Potential options for advancement of insulin therapy to include prandial insulin are prandial premixed therapy (PPT) (12–15) or basal/bolus therapy (BBT) (16–18). BBT is the recommended regimen for insulin intensification (11). However, PPT is a more convenient regimen that has the potential to work as effectively as BBT (12–15). There have been no previous head-to-head studies assessing the effectiveness of analog PPT plus OHAs compared with analog BBT plus OHAs in patients with type 2 diabetes. Thus, in this study we tested the hypothesis that an analog PPT regimen (insulin lispro mixtures three times daily with meals) in combination with OHAs is noninferior in overall glycemic control (A1C) at end point compared with analog BBT (insulin glargine plus mealtime insulin lispro) in combination with OHAs in patients with type 2 diabetes who have failed to achieve glycemic targets with once-daily insulin glargine in combination with OHAs.
This 24-week, randomized, open-label, active-controlled trial was conducted in accordance with the International Conference on Harmonization Guidelines for Good Clinical Practice and the Declaration of Helsinki (19) at 58 centers in the U.S. and Puerto Rico from May 2004 to June 2006. All patients provided written informed consent.
Men and women, aged 30–75 years, with type 2 diabetes (World Health Organization classification) and inadequate glycemic control (A1C
Patients were excluded if they had a history of scheduled mealtime insulin use or more than one episode of severe hypoglycemia within the prior 6 months, BMI >45 kg/m2, or excessive insulin resistance (total daily insulin [TDI] dose >2.0 units/kg). Patients with congestive heart failure requiring pharmacological treatment, functional status of New York Heart Association class III or IV, a history of renal insufficiency (serum creatinine
Study medications and treatments
In addition to scheduled 6-week office visits, patients were contacted weekly during the initial 3 months with adjustment of insulin doses to achieve target preprandial plasma glucose levels <110 mg/dl (<6.1 mmol/l). Insulin doses, self-monitored plasma glucose (SMPG) values, and any events associated with signs or symptoms of hypoglycemia were recorded in diaries.
Safety and tolerability were monitored throughout the study. Events related to hypoglycemia were assessed as to incidence, rate, and severity. Hypoglycemia was reported as any symptomatic event with classic cognitive and/or adrenergic signs with or without plasma glucose confirmation. Confirmed symptomatic hypoglycemia was reported as symptoms of hypoglycemia with plasma glucose levels
Outcome measures
Statistical methods
The primary outcome (change from baseline in A1C) was analyzed by ANCOVA with treatment, dosing algorithm, sex, and baseline A1C as fixed effects. Noninferiority would be claimed if the lower limit of the two-sided 90% CI for the difference in change from baseline A1C did not exceed –0.3%. Secondary outcomes (SMPG, TDI dose, and change in weight) were analyzed by ANCOVA with treatment, dosing algorithm, and sex as fixed effects. Percentage of patients achieving A1C goals (<7.5, <7.0, In contrast with analysis of the primary outcome, safety assessments were based on the entire randomly assigned population. The proportions of patients in each group reporting at least one hypoglycemic event or a severe hypoglycemic event were compared with Fisher's exact test. Hypoglycemic rate and severe hypoglycemic rate were analyzed using ANCOVA with treatment, dose algorithm, and sex as fixed effects. Categorical safety variables were compared between groups with Fisher's exact test.
Patient disposition Of the 547 patients who were screened, 374 were randomly assigned to receive the study treatment (PPT, n = 187; BBT, n = 187). All randomly assigned patients received at least one dose of study medication. A total of 158 patients in each treatment group (84%) completed the protocol. Reasons for early discontinuation are provided in Table 2 of the online appendix. Baseline characteristics were similar between groups (Table 1). The average duration of diabetes was 11 years, baseline weight was 99 kg, and 45% of the study population was non-Caucasian. The numbers of patients taking various combinations of concomitant OHAs at study entry and during the study are shown in Table 2. At study entry, the only difference between groups was that the OHA combination of sulfonylurea and thiazolidinedione was more frequently used in the BBT group (BBT n = 12; PPT n = 3; P = 0.032); however, an equal number of patients in both groups discontinued sulfonylurea treatment upon random assignment (BBT n = 131; PPT n = 130).
Glycemic control Baseline A1C was similar in both groups (PPT 8.8 ± 1.0%; BBT 8.9 ± 1.1%; P = 0.598). Significant decreases in mean A1C values were observed within 6 weeks of therapy initiation for both groups (P < 0.001), and A1C continued to decline throughout the duration of the study. At study end (24 weeks), mean A1C was reduced from baseline by 1.87% in the PPT group to 6.95% and by 2.09% in the BBT group to 6.78% (P = 0.021 for comparison of end point A1C values) (Fig. 1A). The difference in A1C change from baseline to end point (BBT minus PPT) was –0.22%, with a 90% CI of –0.38 to –0.07 (Fig. 1A). The protocol-specified lower limit of the CI required for noninferiority was –0.3%. Thus, noninferiority of PPT was not demonstrated.
The cumulative percentage of patients across A1C values was analyzed. At baseline, the distribution was similar between the two groups (data not shown). By visit 4 (12 weeks), the BBT group began to show a trend toward a greater number of patients achieving target A1C values of <7.0 and 6.5% (data not shown). This trend became statistically significant by the study conclusion; 101 patients (69%) in the BBT group achieved an A1C <7.0% vs. 81 patients (54%) in the PPT group, whereas 74 patients (50%) in the BBT group achieved an A1C 6.5% vs. 53 patients (35%) in the PPT group (Fig. 1B). High percentages of patients receiving both insulin regimens were able to achieve an A1C <7.5% (BBT 83%; PPT 82%). The percentage of patients at specific A1C values is shown in Fig. 1C. Two patients in the PPT group and none in the BBT group had an A1C 10% at 24 weeks. SMPG 8-point profiles, collected at baseline and end point, are shown in Fig. 1D. Both therapies significantly reduced plasma glucose values from baseline at all time points measured. End point profiles collected were similar between the two groups at all time points except fasting and morning 2-h postprandial, for which BBT produced significantly lower plasma glucose (147 ± 43 mg/dl [8.2 ± 2.4 mmol/l] vs. 159 ± 55 mg/dl [8.8 ± 3.0 mmol/l], P = 0.013; and 155 ± 53 mg/dl [8.6 ± 3.0 mmol/l] vs. 174 ± 56 mg/dl [9.6 ± 3.1 mmol/l], P = 0.002).
Insulin dose and weight gain
Safety: hypoglycemia and adverse events There were a total of 9 serious adverse events (SAEs) reported in the PPT group and 13 in the BBT group, and no difference in the incidence of SAEs (6 [3.2%] for PPT vs. 9 [4.8%] for BBT; P = 0.600). No SAEs were identified as potentially being related to the study drug other than hypoglycemia (one event: BBT group).
We report the first head-to-head comparison of two basal/prandial insulin analog regimens (PPT versus BBT) designed to optimize glycemic control in type 2 diabetic patients previously treated with insulin glargine plus oral agents. The difference in A1C change from baseline to end point (BBT minus PPT) was –0.22% (90% CI –0.38 to –0.07); thus, noninferiority of PPT to BBT was not demonstrated based on a prespecified noninferiority margin of 0.3%. More patients in the BBT group reached A1C targets of <7.0 and 6.5%; however, mean end point A1C values for both groups were <7.0%. The slightly lower A1C results in the BBT group compared with the PPT group may be partially accounted for by the significantly lower FPG and morning 2-h postprandial plasma glucose results observed in the BBT group. This result may have reflected the lack of prior clinical experience with titration of lispro mix 50/50. Both insulin regimens caused a modest weight gain of 4–5 kg in conjunction with significant A1C reduction. Intensive insulin therapy is also known to be associated with hypoglycemia, although severe events are infrequent in type 2 diabetes (11,24). This study, using downloadable glucose meter data and patient diaries to capture any occurrence of hypoglycemia, showed that with both insulin regimens the majority of patients experienced at least one episode of self-reported hypoglycemia. In contrast, among all patients, there was a maximum of 6 nocturnal events and 0.1 severe event per patient per year. Clinical studies have been conducted to compare PPT with basal insulin therapy, and other studies have evaluated the safety and efficacy of BBT, but trials evaluating the efficacy of three-times-daily PPT in type 2 diabetic patients previously treated with insulin are few (12,15), as are analog BBT studies (17,18). Differences in insulin titration algorithms and glycemic targets may limit potential theoretical comparisons with these studies. Furthermore, previous trials assessing the efficacy of PPT in type 2 diabetic patients have not used BBT as a comparator. A recent 24-week, parallel-group study by Robbins et al. (15), compared overall glycemic control with lispro mix 50/50 three times daily (plus metformin) to once daily glargine (plus metformin) in type 2 diabetic patients previously treated with OHAs (metformin and/or sulfonylureas) and zero to two daily insulin injections. The end point mean A1C for the lispro mix 50/50 group was similar to our PPT value (7.1 and 6.9%, respectively). The change in A1C from baseline observed in our PPT group (–1.87%) was larger than the comparable value in the lispro mix 50/50 group (–0.7%). However, it should be noted that the Robbins et al. study had a 6-week lead-in period in which patients received twice-daily lispro mix 75/25 and metformin, which may have resulted in a lower baseline A1C of 7.8%. Glycemic control using once-, twice-, or thrice-daily injections of biphasic insulin aspart 70/30 (NovoLog Mix 70/30) was assessed in type 2 diabetic patients in whom OHA treatment with or without basal insulin has failed (The 1-2-3 Study) (12). Treatment with biphasic insulin aspart 70/30 once daily for 16 weeks was started, which was then progressed to twice daily for 16 weeks and finally to thrice daily for 16 weeks if A1C exceeded 6.5% at the end of any phase. Patients were considered completers if they attained target A1C by the end of a phase and were then withdrawn from the study. By combining all three phases, 77% of patients achieved a target A1C <7% at the end point. In the PPT arm of our study, 54% of patients achieved this target. However, the 1-2-3 Study was an uncontrolled, nonrandomized trial with no comparator arm and is therefore of limited comparison value owing to these important methodological limitations. In addition, loss of glycemic control over time would not have been reflected in completer populations of the 1-2-3 Study because of withdrawal of patients upon achievement of the target A1C.
Other studies using basal/bolus insulin therapy (17,18) have demonstrated efficacy and safety findings similar to those observed in our trial. In a recent study, Bergenstal et al. (18) used BBT (glargine/glulisine) to test a premeal glucose pattern algorithm versus carbohydrate counting for dose adjustment of insulin glulisine (Apidra). Similar to our study, eligible subjects in the trial had type 2 diabetes inadequately controlled by previous insulin therapy plus OHAs, an average duration of diabetes of >10 years, and baseline BMI of 36.7 kg/m2. These authors observed a 1.5–1.6% decrease in mean A1C from baseline to end point (8.2 to
Potential limitations of the current study include the open-label design, the possibility that the glargine dose before the study entry was not optimized, and the chance that insulin doses were more aggressively titrated in the BBT arm than in the PPT arm. It should be noted that the average daily prestudy glargine dose for patients in our study was
Both insulin regimens demonstrated a clinically meaningful ability to improve glycemic control, although, based on the prespecified margin, noninferiority of PPT compared with BBT was not demonstrated. This study assessed multiple factors that need to be considered in the individual decision-making process of selecting PPT versus BBT for type 2 diabetic patients requiring insulin advancement, such as the magnitude of desired A1C reduction from baseline, the percentage of patients achieving specific A1C targets, the incidence and severity of hypoglycemia, and the number of required injections. BBT was associated with a greater reduction in A1C from baseline and a larger proportion of patients who achieved A1C targets of <7.0 and
This study was supported by Eli Lilly and Company. The authors thank Dr. Scott Jacober for scientific contributions to the study design, Dr. Pamela Anderson for scientific manuscript review, and Ms. Diana Robertson, Mr. Lyndon Lacaya, and Mr. David Quinn for technical assistance.
Published ahead of print at http://care.diabetesjournals.org on 12 October 2007. DOI: 10.2337/dc07-1122. Clinical trial reg. no. NCT00110370, clinicaltrials.gov. J.R. has received grant support for clinical studies and also consulting fees for serving on advisory boards from Eli Lilly, sanofi-aventis, and Novo Nordisk. A.J.A. has received honoraria for serving on advisory boards of and as a speaker for Eli Lilly and Company and sanofi-aventis. G.C. has received consulting fees for being a member of the Scientific Advisory Board on Erectile Dysfunction and the Diabetes Advisory Board from Eli Lilly and Company. Additional information for this article can be found in an online appendix at http://dx.doi.org/10.2337/dc07-1122. Funding for this study was provided by Eli Lilly and Company. Authors affiliated with Eli Lilly were involved in the study conceptualization, design, and interpretation of results as well as authoring of this article. 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 June 13, 2007. Accepted for publication October 4, 2007.
This article has been cited by other articles:
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||