1. INCRETINS
In response to equivalent hyperglycemic stimuli, ORAL glucose elicits a greater insulin response than IV glucose
Glucagon-like Peptide 1 (GLP-1) and Glucose-Dependent Insulinotrophic Polypeptide (GIP) account for ~90% of the incretin effect

4. Glucose-Stimulated Secretion of Insulin
GLUT2
Glucose
ATP
Pyruvate GK
TCA
Cycle*
Pancreatic β Cell K+
Potassium channel
SUR AC +
GLP-1
GIP
Insulin
[Ca2+]
Triggering
Calcium channel
cAMP
ATP
Amplifying
Glucose-Stimulated Secretion of Insulin
Glucose stimulates insulin secretion by triggering and amplifying pathways.1 The triggering pathway begins with glucose transporters (GLUT2) on the surface of beta cells, which allow glucose to enter the cell.2 Glucose metabolism within the beta cell leads to a series of events that triggers the release of insulin.
(1) After glucose enters the cell, ATP increases, which leads to the closing of the ATP-sensitive potassium channel in the beta-cell membrane. The closure of the potassium channel results in depolarization of the cell membrane and the opening of the calcium channel.1
(2) The glucose-mediated influx of calcium through the channel and the release of intracellular calcium stores cause the release of stored insulin from vesicles near the cell membrane (exocytosis).1 The ATP-sensitive potassium channel may also be closed by the activation of the sulfonylurea receptor without glucose being present.3 The action of the triggering pathway is augmented by an amplifying pathway that is also responsive to glucose metabolism.3
(3) In addition to glucose, the amplifying pathway can also be activated by incretins – GLP-1 and GIP.3,4
GLP-1 and GIP send a signal through their receptors that activates adenylyl cyclase (AC) and generates cAMP from ATP; cAMP in turn activates protein kinase A (PKA).3–5 The GLP-1– and GIP–stimulated increase of cAMP and the activation of PKA via the amplifying pathway augment the effect of increased intracellular calcium generated by glucose through the triggering pathway. This process enhances the release of insulin. cAMP also activates exchange protein activated by cAMP (EPAC) which can stimulate insulin exocytosis independent of PKA.3,4
Thus, in the presence of increased intracellular calcium caused by elevated glucose, GLP-1 and GIP amplify the insulin response to glucose via cAMP production. The triggering pathway must be activated by glucose for the incretin-activated amplifying pathway to have any effect.1 This hierarchy between the 2 pathways helps explain why the action of GLP-1 and GIP is glucose-dependent.
AC = adenylyl cyclase; ATP = adenosine triphosphate; cAMP = cyclic adenosine monophosphate; GK = glucokinase; GLUT2 = glucose transporters; SUR = sulfonylurea receptor; *TCA = Tricarboxylic acid (Krebs cycle).
Hinke SA, et al. J Physiol. 2004;558:
Henquin JC. Diabetes. 2000;49:
Henquin JC. Diabetes. 2004;53(suppl 3):S48-S58.
References:
1. Henquin J-C. Triggering and amplifying pathways of regulation of insulin secretion by glucose. Diabetes. 2000;49:1751–1760.
2. Nussey SS, Whitehead SA. Endocrinology: An Integrated Approach. Oxford, England: BIOS Scientific Publishers Available at: Accessed March 6, 2006.
3. Henquin J-C. Pathways in β-cell stimulus-secretion coupling as targets for therapeutic insulin secretagogues. Diabetes. 2004;53(suppl 3):S48–S58.
4. Hinke SA, Hellemans K, Schuit FC. Plasticity of the β cell insulin secretory competence: preparing the pancreatic β cell for the next meal. J Physiol. 2004;558:369–380.
5. Kieffer TJ, Habener JF. The glucagon-like peptides. Endocr Rev. 1999;20:876–913.

5. MOLECULAR ACTIONS OF GLP-1 ON BETA CELL
INSULIN SECRETION
Holst JJ, Physiol Rev 87: , 2007
Drucker FJ, Cell Metab , 2006
PKA
IC Ca++
Insulin
Secretion
cAMP
Epac2
PI-3K
INSULIN GENE TRANSCRIPTION – Pdx-1
replenishes beta cell insulin stores
prevents beta cell exhaustion
BETA CELL GLUCOSE SENSITIVITY
increased GLUT2 and Glucokinase
restores glucose responsitivity to resistant
beta cells

7. INSULIN RESPONSES TO PHYSIOLOGICAL AND PHARMACOLOGICAL LEVELS OF GLP-1
Physiological GLP-1 levels1 (15 mM hyperglycemic clamp)
Pharmacological GLP-1 levels2 (15 mM hyperglycemic clamp)
6000
GLP-1 infusion-0.5 pmol/kg/min
6000
GLP-1 infusion-1.0 pmol/kg/min
Plasma GLP-1: 46 pM
Healthy controls
Insulin (pmol/L)
4000
4000
Insulin (pmol/L)
Plasma GLP-1: 126 pmol/L
Type 2 diabetes
2000
2000
These two studies indicate that pharmacological doses of GLP-1 may be needed to obtain full benefits in patients with T2D.
In one study 8 obese patients with T2D with poor glycaemic control (HbA1c 8.6±1.3%) underwent a hyperglycaemic clamp (15 mmol/L) with infusion of GLP-1 at a rate of pmol/kg/min (1). Insulin responses were evaluated as the incremental area under the plasma C-peptide curve. For comparison, 8 matched healthy controls were studied. Infusion of GLP-1 at this rate reached a peak GLP-1 concentration of 41 pmol/L in patients with T2D and 46 pmol/L in healthy controls. In controls, physiological levels of GLP-1 resulted in an increase in insulin secretion. In patients with T2D, however, the insulin response to physiological levels of GLP-1 was substantially reduced.
In the other study, 8 patients with T2D (mean HbA1c 7.4%; mean BMI 29.5 kg/m2) underwent a hyperglycemic clamp (15 mmol/L) with infusion at a rate of 1 pmol/kg body weight/min of GLP-1 (7–36) amide (n=8). The insulin responses to GLP-1 stimulation were measured over 2 hours. For comparison, six matched healthy subjects were examined. GLP-1 infusion reached a peak total GLP-1 concentration of 126 pmol/L and augmented the ‘late phase’ (20–120 min) insulin secretion in the patients. The authors concluded that GLP-1 could normalise late-phase insulin secretion in patients with T2D.
References
Højberg P et al. Diabetologia 2009;52:199–207
2. Vilsbøll T et al. Diabetologia 2002;45:1111–1119
Plasma GLP-1: 41 pM
Type 2 diabetes 60
120 60
120
Time (min)
Time (min)
1. Adapted from Højberg P et al. Diabetologia 2009;52:199–207
2. Adapted from Vilsbøll T et al. Diabetologia 2002;45:1111–1119 7

8. EXENATIDE AND LIRAGLUTIDE
Effectively reduce HbA1c
Preserve beta cell function
Promote weight loss
Correct known pathophysiologic defects in T2DM
Do not cause hypoglycemia
Have an excellent safety profile
Rad 03/20/00
Triplitt & DeFronzo, Expert Rev Endo Metab 1:329-41, 2006 8

9. TIME COURSE OF EFFECT OF EXENATIDE Placebo-Controlled Trials
ON HbA1c
Time (weeks) 20 40 60 80
156
0.5
Exenatide-
10 g bid
Placebo
Open-Label Extension
Baseline HbA1C=8.3%
Exenatide-
10 g bid
Required
DISCUSSION POINTS:
--87% of the subjects who completed the 30-week placebo-controlled, double-blind, Phase 3 studies chose to continue in open-label extension (OLE) studies.
--All subjects were given 5 mcg BYETTA for the first 4 weeks of the OLE (overall, Weeks 30 to 34), after which they received 10 mcg BYETTA for the remainder of their participation in the OLE.
--Shown is 82-week data (30 weeks from placebo-controlled, double-blind study and 52 weeks from OLE) for 393 patients.
--Of the 1446 subjects randomized to the three 30 week, blinded, placebo-controlled trials, 1125 completed and were eligible for enrollment into the open label extension studies (OLE).
--Of the 1125 subjects, 977 (87%) enrolled into the OLEs. At the time of this data analysis, 795 had completed treatment through 52 weeks and 393 had completed treatment through 82 weeks.
--Using the intent-to-treat (ITT) and Last Observation Carried Forward (LOCF) analysis method, the 977 ITT population had A1C and weight reductions at 82 weeks consistent with the 82-week completer population shown here.
--Placebo cohort upon receiving BYETTA showed an immediate decrease of A1C similar to that observed with BYETTA treatment in the first 30 weeks.
--Mean A1C reductions from baseline were very similar at 82 weeks (at least -1.1%) for all three original study treatment groups.
--For patients receiving 10 mcg BYETTA for 82 weeks, 51% achieved an A1C of 7% at 82 weeks.
SLIDE BACKGROUND:
--The slight upward trend seen for both the placebo and BYETTA treatment groups from Weeks 18 to 30 likely represents an initial study effect that disappears over time, and is similar in magnitude to the decrease in A1C during the 4-week placebo lead-in period.
DeFronzo et al, Diabetes Care
28: , 2005
D HbA1c (%)
Klonoff et al, Curr Med Res
Opin 24: , 2008
-1.0
-2.0
Placebo-Controlled Trials

10. EFFECT OF EXENATIDE VERSUS GLARGINE INSULIN ON INSULIN SECRETION IN T2DM
Subjects: 59 T2DM; Age = 58y; BMI = 30.5 kg/m2
HBA1c = 7.5%; FPG = 9.1 mM
Rx = Metformin only
Exptl Design: Exenatide*(n=29) vs Glargine (n=30)
Treatment goal = HbA1c ≤ 7.0%
Actual HbA1c = 6.8±0.1% Hyperglycemic (15 mM) clamps
Study Duration: One year
* Up to ug tid

11. C-PEPTIDE SECRETION DURING HYPERGLYCEMIC CLAMP AFTER 1 YEAR OF EXENATIDE VS GLARGINE INSULIN2 4 6 8 10 1 2 3 4
Ratio to Baseline
P<
3.19
1.31
EXEN
GLAR
C-peptide (nmol/L)
Exenatide
Glargine
Glucose 15 mM
-15 10 30 60 80
Time (min)
Exenatide 11

12. DECREMENT IN A1c IN PIVOTAL LIRAGLUTIDE (1.8 mg/d) TRIALS
-1.6
-1.2
-0.8
-0.4
LEAD 3
Mono RX
-1.1
-1.0
-1.1
LEAD 2
MET
LEAD 1 SU
LEAD 4
MET + TZD
LEAD 5
MET + SU
-1.3
-1.5
Percent Reaching
A1c < 7.0%
51%
42%
54%
53%
Buse JB, Lancet 374:39-47, 2009
Garber A, Lancet 373(9662):473-81, 2009
Marre M, Diabet Med 26:268-78, 2009
Nauck MA, Diabetes Care 32:84-90, 2009
Russell-Jones, Diabetologia 52: , 2009
Zinman B, Diabetes Care 32: , 2009

13. Insulin Secretion Rate
A SINGLE DOSE OF LIRAGLUTIDE (7.5 ug/kg) RESTORES BETA CELL INSULIN RESPONSE TO HYPERGLYCEMIA IN T2DM PATIENTS
Chang et al, Diabetes 52: , 2003
Insulin Secretion Rate
(pmol/min kg) 4 8 12
Glucose (mg/dl) 80
120
160
200
240
NGT
Controls
T2DM (Lira)
T2DM (Placebo)

14. EXENATIDE AND LIRAGLUTIDE
Effectively reduce HbA1c
Preserve beta cell function
Promote weight loss
Correct known pathophysiologic defects in T2DM
Do not cause hypoglycemia
Have an excellent safety profile
Rad 03/20/00 14

15. Change in Body Weight (kg) 15-20% reduction in food intake
IMPACT OF EXENATIDE THERAPY OVER 3 YEARS: EFFECT ON A1C AND BODY WEIGHT
Change in A1c (%)
Change in Body Weight (kg)
8.5
15-20% reduction in food intake
8.0 -2
DISCUSSION
Treatment with exenatide resulted in improvements in glycemic control:
Sustained reduction from baseline for A1C at 30 weeks (-1.1 ± 0.1%) and 3 years (-1.0 ± 0.1% (mean ± SE): P< from baseline to 30 weeks and baseline to 3 years)
A1C change of 0.1% between 30 weeks and 3 years (95% CI: 0.03 and 0.36; P=0.02)
A1C change between 1 year and 3 years was statistically significant (P<0.0001)
In the 3-year completer population (N=217)
54% of subjects achieved A1C ≤7% after 30 weeks of exenatide treatment
65% of subjects achieved A1C ≤7% after 52 weeks of exenatide treatment
60% of subjects achieved A1C ≤7% after 82 weeks of exenatide treatment
56% of subjects achieved A1C ≤7% after 104 weeks of exenatide treatment
50% of subjects achieved A1C ≤7% after 130 weeks of exenatide treatment
46% of subjects achieved A1C ≤7% after 156 weeks of exenatide treatment
30% of subjects in the 3-year completer population achieved A1C ≤6.5% after 3 years
Reduction in A1C from baseline in the 3-year eligible ITT population was -0.6 ± 0.1%
SLIDE BACKGROUND
T2DM pts treated with MET and/or SFU were randomized to receive placebo or exenatide in the original placebo-controlled, double-blind, Phase 3, randomized trials and received exenatide in the subsequent open-label extensions
At the time of this analysis, all patients (N=217) had received 3 years of exposure to exenatide
Sustained reduction in FPG after 3 years of ± 4 mg/dL (mean ± SE; P< from baseline)
156-week data is for 217 subjects (Cohorts 1 + 2) who had 3 years of exenatide exposure
Cohort 1: Subjects who received exenatide (not placebo) in the 30-week placebo-controlled trials, continued exenatide treatment throughout participation in the open-label extension trials and subsequent long-term maintenance trial
Therefore, Cohort 1 completed 156 weeks of exenatide exposure at Study Week 156
Cohort 2: Subjects who received placebo in the placebo-controlled trials, then received exenatide treatment from Week 30, the start of the open-label extension trials, and continued in the subsequent long-term maintenance trial
Therefore, Cohort 2 completed 156 weeks of exenatide exposure at Study Week 186
7.5
-1.1 ±0.1%
-1.1 ±0.1% -4
-5.3 ± 0.4 kg
7.0 -6
54%
% achieving A1C £ 7%
46% 26 52 78
104
130
156 26 52 78
104
130
156
Treatment (wk)
Treatment (wk)
N = 217; Mean ± SE
Klonoff DC, et al. Curr Med Res Opin 2008; 24:
Baseline Weight = 99 kg

16. EXENATIDE AND LIRAGLUTIDE
Effectively reduce HbA1c
Preserve beta cell function
Promote weight loss
Correct known pathophysiologic defects in T2DM
Do not cause hypoglycemia
Have an excellent safety profile
Rad 03/20/00 16