© 2005 by the American Diabetes Association, Inc.
Initiating Insulin Therapy in Type 2 DiabetesA comparison of biphasic and basal insulin analogs
1 University of Texas, Southwestern Medical Center, Dallas, Texas Address correspondence and reprint requests to Philip Raskin, MD, Department of Internal Medicine, Southwestern Medical Center at Dallas, Dallas, TX 75390-8858. E-mail: philip.raskin{at}utsouthwestern.edu
OBJECTIVESafety and efficacy of biphasic insulin aspart 70/30 (BIAsp 70/30, prebreakfast and presupper) were compared with once-daily insulin glargine in type 2 diabetic subjects inadequately controlled on oral antidiabetic drugs (OADs).
RESEARCH DESIGN AND METHODSThis 28-week parallel-group study randomized 233 insulin-naive patients with HbA1c values
RESULTSA total of 209 subjects completed the study. At study end, the mean HbA1c value was lower in the BIAsp 70/30 group than in the glargine group (6.91 ± 1.17 vs. 7.41 ± 1.24%, P < 0.01). The HbA1c reduction was greater in the BIAsp 70/30 group than in the glargine group (2.79 ± 0.11 vs. 2.36 ± 0.11%, respectively; P < 0.01), especially for subjects with baseline HbA1c >8.5% (3.13 ± 1.63 vs. 2.60 ± 1.50%, respectively; P < 0.05). More BIAsp 70/30treated subjects reached target HbA1c values than glargine-treated subjects (HbA1c CONCLUSIONSIn subjects with type 2 diabetes poorly controlled on OADs, initiating insulin therapy with twice-daily BIAsp 70/30 was more effective in achieving HbA1c targets than once-daily glargine, especially in subjects with HbA1c >8.5%.
Abbreviations: FPG, fasting plasma glucose OAD, oral antidiabetic drug TZD, thiazolidinedione SMPG, self-measured plasma glucose
The U.K. Prospective Diabetes Study demonstrated that most patients with type 2 diabetes will need treatment with exogenous insulin at some point during their lifetimes (1,2). Diminished insulin secretion due to declining ß-cell function eventually results in a loss of glycemic control obtainable with oral antidiabetic drugs (OADs) (3). Common options for insulin initiation include treatment with an intermediate- or long-acting basal insulin (4) or with a biphasic insulin formulation containing both basal and rapid-acting components (5).
Monnier et al. (6) have shown that postprandial glycemic control accounts for NovoLog Mix 70/30 (BIAsp 70/30) is a biphasic insulin analog formulation of insulin aspart containing 30% soluble insulin aspart and 70% insulin aspart crystallized with protamine. When injected at mealtime, BIAsp 70/30 results in improved postprandial glucose levels compared with biphasic human insulin 70/30 (1012). In type 2 diabetic patients beginning insulin therapy, once-daily suppertime (evening) injection of BIAsp 70/30 used in combination with metformin was effective in decreasing HbA1c values in type 2 diabetic patients with inadequate glycemic control on previous OAD therapy (5). With the growing recognition of postprandial glucose control for achieving glycemic targets and the ability of BIAsp 70/30 to control both fasting and postprandial hyperglycemia, we conducted a treat-to-target trial to compare the safety and efficacy of twice-daily BIAsp 70/30 and once-daily insulin glargine therapy in insulin-naive type 2 diabetic subjects.
This was a 28-week randomized, multicenter, open-label, parallel-group, treat-to-target study with a 4-week metformin optimization period (with or without thiazolidinediones [TZDs]). Subjects were randomized to either twice-daily BIAsp 70/30 before breakfast and supper or once-daily glargine at bedtime. The lowest available randomization number was used within each center to provide a balanced treatment assignment. Subjects were also stratified based on TZD use. Subjects and investigators were masked to treatment sequence up to the point of subject randomization. The study was conducted at 25 centers in the U.S., in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines (13). All subjects provided written informed consent.
The study randomized 233 insulin-naive subjects with type 2 diabetes who were 1875 years old and had a BMI
During the 4-week metformin run-in period, metformin was optimized to 1,5002,550 mg/day and subjects discontinued secretagogues and
Insulin therapy was initiated at a total daily dose of 10 units for subjects with FPG values <180 mg/dl or 12 units for subjects with FPG values Insulin doses were titrated weekly for the first 12 weeks and then every 2 weeks thereafter to achieve target FPG and presupper plasma glucose values of 80110 mg/dl. Presupper BIAsp 70/30 and bedtime glargine doses were titrated based on FPG values. The prebreakfast BIAsp 70/30 dose was titrated based on presupper SMPG values. Dose titration was based on plasma glucose values from the preceding 3 days (measured with a OneTouch Ultra blood glucose meter; LifeScan). If two of the three readings for a specified time period (prebreakfast or presupper) were not within target, the insulin dose was adjusted based on the lower of the two plasma glucose readings unless hypoglycemia was occurring. Prebreakfast and presupper BIAsp 70/30 doses were adjusted independently of each other as follows: decreased by 2 units if plasma glucose was <80 mg/dl, no change if plasma glucose was 80110 mg/dl, increased by 2 units if plasma glucose was 111140 mg/dl, increased by 4 units if plasma glucose was 141180 mg/dl, and increased by 6 units if plasma glucose was >180 mg/dl. Glargine was adjusted according to FPG with an algorithm similar to that used in the Treat-to-Target study (4): decreased by 2 units if plasma glucose was <80 mg/dl, no change if plasma glucose was 80110 mg/dl, increased by 24 units if plasma glucose was 111140 mg/dl, increased by 46 units if plasma glucose was 141180 mg/dl, and increased by 68 units if plasma glucose was >180 mg/dl. The increase in the total daily dose was not to exceed the greater of 10 units or 10% of the current total daily dose.
Efficacy assessments
Safety assessments
Statistical analysis
Subjects A total of 263 subjects were enrolled into the 4-week metformin run-in period. There were 30 subjects who failed the run-in period, and 233 were randomized to insulin treatment. Baseline demographic characteristics were similar between treatment groups (Table 1). Most (n = 209, 90%) subjects completed the study. A total of 24 subjects discontinued the study; 17 subjects from the BIAsp 70/30 group and 7 from the glargine group (Table 1). The intent-to-treat population included 108 subjects in the BIAsp 70/30 group and 114 subjects in the glargine group.
Efficacy At the end of the study, the mean HbA1c values were lower for the BIAsp 70/30 group compared with the glargine group (6.91 ± 1.17 vs. 7.41 ± 1.24%, P < 0.01), and the overall reduction in HbA1c for subjects in the BIAsp 70/30 group was significantly greater than for subjects in the glargine group (2.79 ± 0.11 vs. 2.36 ± 0.11%, respectively; P < 0.01). The HbA1c reduction was even larger for subjects whose baseline HbA1c values were >8.5% (3.13 ± 1.63 vs. 2.60 ± 1.50%, P < 0.05, BIAsp 70/30 vs. glargine, respectively). In subjects with baseline HbA1c 8.5%, the absolute HbA1c reductions were less pronounced and were comparable between treatment groups (1.40 ± 0.53 vs. 1.42 ± 0.59%, BIAsp 70/30 vs. glargine, P > 0.05). For all subjects in each treatment group, a greater percentage of the BIAsp 70/30 group achieved target HbA1c values <7.0 and 6.5% than in the glargine group (Fig. 1).
The similar percentage of subjects in each group (32 vs. 33%) was taking pioglitazone before and during the study (Table 1). Subjects treated with a TZD before the study had slightly lower baseline HbA1c values than subjects not treated with a TZD (Table 1). The end-of-study HbA1c values (±SD) were significantly lower in the BIAsp 70/30 group regardless of pioglitazone use during the study (with pioglitazone: 6.8 ± 0.9 vs. 7.4 ± 1.1%, P = 0.014; without pioglitazone: 7.0 ± 1.3 vs. 7.4 ± 1.3%, P = 0.037, for BIAsp 70/30 vs. glargine, respectively). The end-of-study HbA1c reductions from baseline were significantly greater for the BIAsp 70/30 group regardless of pioglitazone use (with pioglitazone: 2.60 ± 0.16 vs. 2.13 ± 0.16%, P < 0.05; without pioglitazone: 2.89 ± 0.15 vs. 2.46 ± 0.14%, P < 0.05, BIAsp 70/30 vs. glargine, respectively). FPG values were similar at baseline (252 ± 67.4 vs. 243 ± 68.8 mg/dl, BIAsp 70/30 vs. glargine, respectively; P > 0.05) and at the end of the study (127 ± 40.6 vs. 117 ± 44.3 mg/dl, P > 0.05). The FPG in the glargine group was similar to the 116 mg/dl found in the Treat-to-Target study (4). Target FPG (80110 mg/dl) at the end of the study was achieved by 57 and 36% of the subjects in the glargine and BIAsp 70/30 groups, respectively. The change-from-baseline FPG values were the same for each treatment group (125 ± 72.9 vs. 125 ± 74.4 mg/dl, BIAsp 70/30 vs. glargine, respectively).
Both treatment groups had improvements from baseline in their eight-point SMPG profile (Fig. 2). At the end of the study, SMPG values before lunch and supper, after supper, and at bedtime were significantly less for the BIAsp 70/30 group (Fig. 2). Except for lunch, mean prandial plasma glucose increments (postprandial plasma glucose minus preprandial plasma glucose values) were less for BIAsp 70/30 than for glargine (breakfast: 33.9 ± 46.9 vs. 55.3 ± 49.9 mg/dl, P < 0.01; lunch: 44.5 ± 48.8 vs. 32.5 ± 53.9 mg/dl, P > 0.05; supper: 19.0 ± 62.7 vs. 41.8 ± 52.8 mg/dl, P < 0.05). Overall postprandial glycemic exposure was
Although initial daily insulin doses were similar in both groups (0.14 ± 0.03 vs. 0.13 ± 0.03 units/kg for BIAsp 70/30 vs. glargine, respectively), insulin doses at the end of the study were greater for the BIAsp 70/30 group than for the glargine group (total units: 78.5 ± 39.5 vs. 51.3 ± 26.7 units; for units by weight, 0.82 ± 0.40 vs. 0.55 ± 0.27 units/kg, P < 0.05). Despite independent titration of the prebreakfast and presupper doses, the total daily dose of BIAsp 70/30 at the end of the study was equally divided between prebreakfast and presupper (38.7 ± 20.4 and 39.9 ± 20.7 units, respectively). The mean total daily insulin dose was 21 units lower in subjects in the BIAsp 70/30 group taking pioglitazone (64.2 ± 33.8 units) compared with those not taking pioglitazone (85.4 ± 40.4 units). Mean total insulin doses of glargine were similar for subjects with or without pioglitazone treatment (53.0 ± 26.4 and 50.5 ± 26.9 units, respectively). Mean body weight increased in both treatment groups at the end of the study (BIAsp 70/30, 5.4 ± 4.8 kg, vs. glargine, 3.5 ± 4.5 kg, P < 0.01). The weight gain was similar for both treatments when subjects were taking pioglitazone during the study (5.1 ± 5.1 vs. 4.5 ± 4.6 kg, BIAsp 70/30 vs. glargine, respectively, P > 0.05). However, in subjects not taking pioglitazone, weight gain was significantly greater in the BIAsp 70/30 group (5.6 ± 4.6 vs. 3.0 ± 4.3 kg, BIAsp 70/30 vs. glargine, respectively; P < 0.01).
Safety The number and type of reported adverse events were similar for the two treatment groups and were not unexpected for the trial population. No end-of-study differences in blood chemistry or hematology laboratory values were noted and mean values for vital signs at the end of the study were similar to baseline values.
This study evaluated two approaches for initiating insulin therapy in type 2 diabetic patients who have failed to achieve target glycemic control goals on OAD therapy. Initiating insulin therapy with twice-daily BIAsp 70/30 provided significantly improved overall glycemic control as measured by a lower end-of-study HbA1c value compared with once-daily insulin glargine. The reductions in HbA1c provided a significant and clinically relevant treatment improvement (HbA1c difference of 0.43%) for subjects in the BIAsp 70/30 group, allowing significantly more BIAsp 70/30treated subjects to achieve HbA1c targets established by the American Diabetes Association. Notably, BIAsp 70/30 was significantly more effective than insulin glargine in reducing HbA1c for subjects who entered the present study with HbA1c values >8.5%. This is consistent with the fact that as ß-cell function declines, HbA1c rises, and basal insulin replacement alone is insufficient to control postprandial hyperglycemia. The results of this study were comparable to a similar study where insulin therapy was initiated with either twice-daily biphasic insulin lispro 75/25 or once-daily glargine, both taken concomitantly with metformin (14). Reduction in HbA1c was greater in the lispro premix group, and more subjects reached target HbA1c <7% in 16 weeks when treated with lispro premix than with glargine (41 vs. 22%, P < 0.001). In another study, therapy with once-daily glargine plus sulfonylureas and metformin was compared with twice-daily biphasic human insulin premix alone, without OADs (15). Although greater HbA1c reduction was observed in the glargine group at 24 weeks, the human premix group may have been disadvantaged by the removal of OADs from the therapeutic regimen, specifically metformin, which has been shown to be very efficacious when used in combination with insulin therapy (16). Additionally, a biphasic human insulin mix formulation was used, not an analog mix that would have provided greater postprandial glycemic control than the human premix (10). In the present study, the withdrawal of secretagogues from both treatment arms may have disadvantaged insulin glargine. However, it is questionable whether secretagogues would provide significant benefit in subjects with baseline HbA1c values >8.5%. Regardless of secretagogue use, this study used a treat-to-target regimen to optimize insulin therapy, such that the mean FPG in the glargine group at the end of the study was similar to that achieved with glargine in the Treat-to-Target study (4). Biphasic analog insulin mixes have an advantage over basal insulin alone because they provide the rapid-acting insulin analog insulin aspart as the soluble component that covers mealtime glycemic needs (11,12,17). In this trial, the plasma glucose increments for breakfast and supper, as well as the overall plasma glucose increment for the three meals, were significantly less in the BIAsp 70/30 group. The proposed 5070% contribution of postprandial glycemic control to overall glycemic control as subjects get closer to achieving glycemic targets would give subjects treated with BIAsp 70/30 an advantage in getting to HbA1c target compared with subjects treated with only basal insulin (6). The rate of hypoglycemia typically increases as patients use insulin to attain better glycemic control and defined glycemic targets. It is not surprising that the overall rate of minor hypoglycemia was greater in the BIAsp 70/30 group than in the glargine group considering that the BIAsp 70/30 group had better glycemic control than the glargine group. Importantly, hypoglycemia was not a barrier to achieving glycemic targets for the BIAsp 70/30 group. Because intensive glycemic control using insulin is associated with an increased risk of hypoglycemia (18), all patients initiating insulin therapy should always be referred to diabetes self-management training programs to help them prevent, recognize, and manage their hypoglycemic episodes.
Initiation of insulin therapy is often accompanied by an increase in weight as glycemic control improves. The BIAsp 70/30 group had its greatest increase in weight (1.3 kg) within the first month of therapy; lesser weight increases occurred during subsequent months until the increase was 0.8 and 0.4 kg in months 5 and 6 of the study. The glargine group had consistent weight increases during the study, Insulin therapy is typically begun only after lifestyle modification and OAD therapy fail to normalize HbA1c values. In the authors experience, most individuals with type 2 diabetes rarely are started on insulin with HbA1c values <8.5%. Unfortunately, many subjects will have had type 2 diabetes for 1015 years before diagnosis and may have already developed complications (19). Therefore, earlier introduction of the most effective insulin therapy should be encouraged despite the reluctance of patients and their physicians (20). Based on the results of this study, biphasic insulin aspart 70/30 appears to be more effective than insulin glargine and a reasonable choice to initiate insulin therapy in insulin-naive subjects with type 2 diabetes that is not optimally controlled on OAD therapy, particularly for those subjects whose HbA1c before insulin initiation is >8.5%.
The INITIATE Study Group includes the following investigators: Bruce Bode, Peter Bressler, Robert Gabbay, Alan Garber, G. Murthy Gollapudi, Brent Gooch, Priscilla Hollander, Roy Kaplan, William Kaye, Leslie Klaff, Wendy A. Lane, Andrew Lewin, John Liljenquist, Dennis Linden, Eric Maybach, Kwame Osei, Philip Raskin, Raymond Reynolds, Julio Rosenstock, Sherwyn Schwartz, Phillip Snell, Danny Sugimoto, Gregory Waser, Richard Weinstein, and Kevin Wietecha.
This clinical trial was financially supported by Novo Nordisk. Appreciation is given to the following clinical coordinators at each site: Cecelia Boyer, Allison Camacho, Deanna Clay, Nelly Delgado, Judith Dillon, Julie Domsch, Bari Dorward, Nancy Durham, Donna Flanders, Kai French, Penelope Greenwell, Sarah Hale, Autumn Hernandez, Ruth Holt, Sujata Jingouda, Lisa Martin, Debra Nichols, Ana Melendez, Yolanda Messer, Tatyana Noryan, Krysti Pettingill, Greg Plummer, Jill Prado, Mary Ramey, Judith Silverstein, Sophia Stalters, Jaymey Sweeney, Vimal Taneja, and Patria Ybanez.
* A complete listing of INITIATE Study Group members can be found in the APPENDIX. P.R. is a member of an advisory panel for and has received honoraria, consulting fees, and research support from Novo Nordisk. A.L. has received honoraria from Novo Nordisk. R.A.G. has received research support from Novo Nordisk and has participated in speakers bureaus for Novo Nordisk, GlaxoSmithKline, Pfizer, Aventis, and Merck. B.B. is a member of an advisory board for and has received honoraria and grant/research support from Novo Nordisk. A.G. has received grant/research support from Bristol-Myers Squibb, GlaxoSmithKline, Novo Nordisk, Schering-Plough, Novartis, Roche, Astra-Zeneca, Merck, and Fujisawa; has acted as a consultant for Bristol-Myers Squibb, GlaxoSmithKline, and Novo Nordisk; and has participated in speakers bureaus for Bristol-Myers Squibb, GlaxoSmithKline, Eli Lilly, Novo Nordisk, Pfizer, Wyeth-Ayerst, and Aventis. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. See accompanying editorial, p. 494. Received for publication October 21, 2004. Accepted for publication November 2, 2004.
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