Antoine Makdissi

Sitagliptin exerts an antinflammatory action.

CONTEXT Sitagliptin is an inhibitor of the enzyme dipeptidyl peptidase-IV (DPP-IV), which degrades the incretins, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, and thus, sitagliptin increases their bioavailability. The stimulation of insulin and the suppression of glucagon secretion that follow exert a glucose lowering effect and hence its use as an antidiabetic drug. Because DPP-IV is expressed as CD26 on cell membranes and because CD26 mediates proinflammatory signals, we hypothesized that sitagliptin may exert an antiinflammatory effect. PATIENTS AND METHODS Twenty-two patients with type 2 diabetes were randomized to receive either 100 mg daily of sitagliptin or placebo for 12 wk. Fasting blood samples were obtained at baseline and at 2, 4, and 6 hours after a single dose of sitagliptin and at 2, 4, 8, and 12 wk of treatment. RESULTS Glycosylated hemoglobin fell significantly from 7.6 ± 0.4 to 6.9 ± 3% in patients treated with sitagliptin. Fasting glucagon-like peptide-1 concentrations increased significantly, whereas the mRNA expression in mononuclear cell of CD26, the proinflammatory cytokine, TNFα, the receptor for endotoxin, Toll-like receptor (TLR)-4, TLR-2, and proinflammatory kinases, c-Jun N-terminal kinase-1 and inhibitory-κB kinase (IKKβ), and that of the chemokine receptor CCR-2 fell significantly after 12 wk of sitagliptin. TLR-2, IKKβ, CCR-2, and CD26 expression and nuclear factor-κB binding also fell after a single dose of sitagliptin. There was a fall in protein expression of c-Jun N-terminal kinase-1, IKKβ, and TLR-4 and in plasma concentrations of C-reactive protein, IL-6, and free fatty acids after 12 wk of sitagliptin. CONCLUSIONS These effects are consistent with a potent and rapid antiinflammatory effect of sitagliptin and may potentially contribute to the inhibition of atherosclerosis. The suppression of CD26 expression suggests that sitagliptin may inhibit the synthesis of DPP-IV in addition to inhibiting its action.

Liraglutide as additional treatment for type 1 diabetes

OBJECTIVE To determine whether the addition of liraglutide to insulin to treat patients with type 1 diabetes leads to an improvement in glycemic control and diminish glycemic variability. SUBJECTS AND METHODS In this study, 14 patients with well-controlled type 1 diabetes on continuous glucose monitoring and intensive insulin therapy were treated with liraglutide for 1 week. Of the 14 patients, eight continued therapy for 24 weeks. RESULTS In all the 14 patients, mean fasting and mean weekly glucose concentrations significantly decreased after 1 week from 130±10 to 110±8  mg/dl (P<0.01) and from 137.5±20 to 115±12  mg/dl (P<0.01) respectively. Glycemic excursions significantly improved at 1 week. The mean s.d. of glucose concentrations decreased from 56±10 to 26±6  mg/dl (P<0.01) and the coefficient of variation decreased from 39.6±10 to 22.6±7 (P<0.01). There was a concomitant fall in the basal insulin from 24.5±6 to 16.5±6 units (P<0.01) and bolus insulin from 22.5±4 to 15.5±4 units (P<0.01). In patients who continued therapy with liraglutide for 24 weeks, mean fasting, mean weekly glucose concentrations, glycemic excursions, and basal and bolus insulin dose also significantly decreased (P<0.01). HbA1c decreased significantly at 24 weeks from 6.5 to 6.1% (P=0.02), as did the body weight by 4.5±1.5  kg (P=0.02). CONCLUSION Liraglutide treatment provides an additional strategy for improving glycemic control in type 1 diabetes. It also leads to weight loss.

Exenatide Exerts a Potent Antiinflammatory Effect

OBJECTIVE Our objective was to determine whether exenatide exerts an antiinflammatory effect. RESEARCH DESIGN AND METHODS Twenty-four patients were prospectively randomized to be injected sc with either exenatide 10 μg twice daily [n = 12; mean age = 56 ± 3 yr; mean body mass index = 39.8 ± 2 kg/m(2); mean glycosylated hemoglobin (HbA1c) = 8.6 ± 0.4%] or placebo twice daily (n = 12; mean age = 54 ± 4 yr; mean body mass index = 39.1 ± 1.6 kg/m(2); mean HbA1c = 8.5 ± 0.3%) for 12 wk. Fasting blood samples were obtained at 0, 3, 6, and 12 wk. Blood samples were also collected for up to 6 h after a single dose of exenatide (5 μg) or placebo. RESULTS Fasting blood glucose fell from 139 ± 17 to 110 ± 9 mg/dl, HbA1c from 8.6 ± 0.4 to 7.4 ± 0.5% (P < 0.05), and free fatty acids by 21 ± 5% from baseline (P < 0.05) with exenatide. There was no weight loss. There was a significant reduction in reactive oxygen species generation and nuclear factor-κB binding by 22 ± 9 and 26 ± 7%, respectively, and the mRNA expression of TNFα, IL-1β, JNK-1, TLR-2, TLR-4, and SOCS-3 in mononuclear cells by 31 ± 12, 22 ± 10, 20 ± 11, 22 ± 9, 16 ± 7, and 31 ± 10%, respectively (P < 0.05 for all) after 12 wk of exenatide. After a single injection of exenatide, there was a reduction by 20 ± 7% in free fatty acids, 19 ± 7% in reactive oxygen species generation, 39 ± 11% in nuclear factor-κB binding, 18 ± 9% in TNFα expression, 26 ± 7% in IL-1β expression, 18 ± 7% in JNK-1 expression, 24 ± 12% in TLR-4 expression, and 23 ± 11% in SOCS-3 expression (P < 0.05 for all). The plasma concentrations of monocyte chemoattractant protein-1, matrix metalloproteinase-9, serum amyloid A, and IL-6 were suppressed after 12 wk exenatide treatment by 15 ± 7, 20 ± 11, 16 ± 7, and 22 ± 12%, respectively (P < 0.05 for all). CONCLUSIONS Exenatide exerts a rapid antiinflammatory effect at the cellular and molecular level. This may contribute to a potentially beneficial antiatherogenic effect. This effect was independent of weight loss.

Insulin Resistance and Inflammation in Hypogonadotropic Hypogonadism and Their Reduction After Testosterone Replacement in Men With Type 2 Diabetes.

OBJECTIVE One-third of men with type 2 diabetes have hypogonadotropic hypogonadism (HH). We conducted a randomized placebo-controlled trial to evaluate the effect of testosterone replacement on insulin resistance in men with type 2 diabetes and HH. RESEARCH DESIGN AND METHODS A total of 94 men with type 2 diabetes were recruited into the study; 50 men were eugonadal, while 44 men had HH. Insulin sensitivity was calculated from the glucose infusion rate (GIR) during hyperinsulinemic-euglycemic clamp. Lean body mass and fat mass were measured by DEXA and MRI. Subcutaneous fat samples were taken to assess insulin signaling genes. Men with HH were randomized to receive intramuscular testosterone (250 mg) or placebo (1 mL saline) every 2 weeks for 24 weeks. RESULTS Men with HH had higher subcutaneous and visceral fat mass than eugonadal men. GIR was 36% lower in men with HH. GIR increased by 32% after 24 weeks of testosterone therapy but did not change after placebo (P = 0.03 for comparison). There was a decrease in subcutaneous fat mass (−3.3 kg) and increase in lean mass (3.4 kg) after testosterone treatment (P < 0.01) compared with placebo. Visceral and hepatic fat did not change. The expression of insulin signaling genes (IR-β, IRS-1, AKT-2, and GLUT4) in adipose tissue was significantly lower in men with HH and was upregulated after testosterone treatment. Testosterone treatment also caused a significant fall in circulating concentrations of free fatty acids, C-reactive protein, interleukin-1β, tumor necrosis factor-α, and leptin (P < 0.05 for all). CONCLUSIONS Testosterone treatment in men with type 2 diabetes and HH increases insulin sensitivity, increases lean mass, and decreases subcutaneous fat.

Liraglutide as additional treatment to insulin in obese patients with type 1 diabetes mellitus.

OBJECTIVE Because approximately 40% of patients with type 1 diabetes have the metabolic syndrome, we tested the hypothesis that addition of liraglutide to insulin in obese patients with type 1 diabetes will result in an improvement in plasma glucose concentrations, a reduction in hemoglobin A1c (HbA1c), a fall in systolic blood pressure, and weight loss. METHODS This is a retrospective analysis of data obtained from 27 obese patients with type 1 diabetes treated with liraglutide in addition to insulin. Patients were also treated for hypertension. Paired t tests were used to compare the changes in HbA1c, insulin doses, body weight, body mass index, 4-week mean blood glucose concentrations (28-day insulin pump mean blood glucose), blood pressure, and lipid parameters prior to and 180 ± 14 days after liraglutide therapy. RESULTS Mean glucose concentrations fell from 191 ± 6 to 170 ± 6 mg/dL (P = .002). HbA1c fell from 7.89 ± 0.13% to 7.46 ± 0.13% (P = .001), without an increase in frequency of hypoglycemia. Mean body weight fell from 96.20 ± 3.68 kg to 91.56 ± 3.78 kg (P<.0001). Daily total and bolus doses of insulin fell from 73 ± 6 to 60 ± 4 (P = .008) units and from 40 ± 5 to 29 ± 3 units (P = .011), respectively. Mean systolic blood pressure fell from 130 ± 3 to 120 ± 4 mm Hg (P = .020). CONCLUSION Addition of liraglutide to insulin in obese patients with type 1 diabetes mellitus leads to improvements in glycemic control and HbA1c and to reductions in insulin dose, systolic blood pressure, and body weight.

Clinical use of liraglutide in type 2 diabetes and its effects on cardiovascular risk factors.

OBJECTIVE To assess whether liraglutide, a glucagon-like peptide-1 receptor agonist, has cardioprotective properties in addition to its glycemic effects. METHODS We performed a retrospective analysis of medical records of 110 obese patients with type 2 diabetes mellitus treated with liraglutide for at least 6 months between March 2010 and April 2011 at our tertiary care referral center. The variables analyzed were body mass index, hemoglobin A(1c) (A1C), systolic blood pressure (SBP), plasma C-reactive protein (CRP) concentrations, and serum lipids. RESULTS In our overall study cohort, we noted a reduction in mean weight from 120 ± 5 kg to 115 ± 3 kg and a decrease in mean A1C from 7.8% ± 0.6% to 7.2% ± 0.2%. The mean triglyceride concentration decreased from 173 ± 19 mg/dL to 151 ± 15 mg/dL, the mean SBP was reduced from 132 ± 6 mm Hg to 125 ± 4 mm Hg, and the mean CRP concentration declined from 4.7 ± 0.8 mg/L to 3.2 ± 0.4 mg/L after treatment with liraglutide for a minimal duration of 6 months and a mean duration of 7.5 months (for all the foregoing changes, P<.05). These variables decreased whether these patients were previously treated with orally administered hypoglycemic agents alone or in combination with insulin or exenatide. CONCLUSION Our findings in a clinical practice show that liraglutide is a potent antidiabetes drug, whether given in combination with orally administered agents or insulin or as a substitution for exenatide. It lowers body weight, A1C levels, SBP, and CRP and triglyceride concentrations.

Reduction of false-negative results in inferior petrosal sinus sampling with simultaneous prolactin and corticotropin measurement.

OBJECTIVE To investigate the value of prolactin as an independent marker of catheter placement to improve the diagnostic accuracy of inferior petrosal sinus sampling (IPSS) in patients with corticotropin-dependent Cushing syndrome. METHODS In this retrospective cohort study, we reviewed hospital records of patients who underwent IPSS procedures at the Cleveland Clinic between 1997 and 2009. Serum prolactin and plasma corticotropin levels were measured prospectively in peripheral and inferior petrosal sinus (IPS) samples. RESULTS Forty-one patients underwent 42 IPSS procedures at our institution during the study period. Among 35 patients with Cushing disease, 1 patient had erroneous IPSS results: all pre-corticotropin-releasing hormone (CRH) and post-CRH IPS to peripheral (IPS:P) ACTH ratios were less than 2 and less than 3, respectively. Despite radiologic evidence of appropriate IPS catheter placement, concurrent IPS:P prolactin ratios indicated that successful IPS venous sampling was not achieved. A second case with equivocal IPSS results could also be explained by corresponding IPS:P prolactin ratios. During IPSS, all patients with an identifiable ACTH-staining adenoma localizing to 1 side of the pituitary gland (n = 22) who demonstrated absent IPS:P ACTH gradients (<2 before or <3 after CRH administration) on the ipsilateral side of the corticotroph adenoma had corresponding IPS:P prolactin ratios less than 1.3. CONCLUSIONS Measurement of prolactin during IPSS testing may reduce false-negative results in patients with Cushing disease who do not demonstrate an appropriate central-to-peripheral ACTH gradient. In our series, all false-negative IPS:P ACTH ratios had a corresponding IPS:P prolactin ratio less than 1.3.

Addition of Liraglutide to Insulin in Patients With Type 1 Diabetes: A Randomized Placebo-Controlled Clinical Trial of 12 Weeks

OBJECTIVE To investigate whether addition of three different doses of liraglutide to insulin in patients with type 1 diabetes (T1D) results in significant reduction in glycemia, body weight, and insulin dose. RESEARCH DESIGN AND METHODS We randomized 72 patients (placebo = 18, liraglutide = 54) with T1D to receive placebo and 0.6, 1.2, and 1.8 mg liraglutide daily for 12 weeks. RESULTS In the 1.2-mg and 1.8-mg groups, the mean weekly reduction in average blood glucose was −0.55 ± 0.11 mmol/L (10 ± 2 mg/dL) and −0.55 ± 0.05 mmol/L (10 ± 1 mg/dL), respectively (P < 0.0001), while it remained unchanged in the 0.6-mg and placebo groups. In the 1.2-mg group, HbA1c fell significantly (−0.78 ± 15%, −8.5 ± 1.6 mmol/mol, P < 0.01), while it did not in the 1.8-mg group (−0.42 ± 0.15%, −4.6 ± 1.6 mmol/mol, P = 0.39) and 0.6-mg group (−0.26 ± 0.17%, −2.8 ± 1.9 mmol/mol, P = 0.81) vs. the placebo group (−0.3 ± 0.15%, −3.3 ± 1.6 mmol/mol). Glycemic variability was reduced by 5 ± 1% (P < 0.01) in the 1.2-mg group only. Total daily insulin dose fell significantly only in the 1.2-mg and 1.8-mg groups (P < 0.05). There was a 5 ± 1 kg weight loss in the two higher-dose groups (P < 0.05) and by 2.7 ± 0.6 kg (P < 0.01) in the 0.6-mg group vs. none in the placebo group. In the 1.2- and 1.8-mg groups, postprandial plasma glucagon concentration fell by 72 ± 12% and 47 ± 12%, respectively (P < 0.05). Liraglutide led to higher gastrointestinal adverse events (P < 0.05) and ≤1% increases (not significant) in percent time spent in hypoglycemia (<55 mg/dL, 3.05 mmol/L). CONCLUSIONS Addition of 1.2 mg and 1.8 mg liraglutide to insulin over a 12-week period in overweight and obese patients with T1D results in modest reductions of weekly mean glucose levels with significant weight loss, small insulin dose reductions, and frequent gastrointestinal side effects. These findings do not justify the use of liraglutide in all patients with T1D.

Insulin Suppresses the Expression of Amyloid Precursor Protein, Presenilins, and Glycogen Synthase Kinase-3β in Peripheral Blood Mononuclear Cells

OBJECTIVE Our objective was to determine whether peripheral blood mononuclear cells express amyloid precursor protein (APP) and other mediators involved in the pathogenesis of Alzheimers disease and whether their expression is suppressed by insulin. RESEARCH DESIGN AND METHODS Ten obese type 2 diabetic patients were infused with insulin (2 U/h with 100 ml 5% dextrose/h) for 4 h. Patients were also infused with 5% dextrose/h or normal physiological saline for 4 h, respectively, on two other days as controls. Blood samples were obtained at 0, 2, 4, and 6 h. RESULTS Insulin infusion significantly suppressed the expression of APP, presenilin-1, presenilin-2, and glycogen synthase kinase-3β in peripheral blood mononuclear cells. Dextrose and saline infusions did not alter these indices. Insulin infusion also caused significant parallel reductions in nuclear factor-κB binding activity and plasma concentrations of serum amyloid A and intercellular adhesion molecule-1. CONCLUSIONS A low dose infusion of insulin suppresses APP, presenilin-1, presenilin-2, and glycogen synthase kinase-3β, key proteins involved in the pathogenesis of Alzheimers disease, in parallel with exerting its other antiinflammatory effects.

Dapagliflozin as Additional Treatment to Liraglutide and Insulin in Patients With Type 1 Diabetes

CONTEXT It is imperative that novel approaches to treatment of type 1 diabetes (T1D) are devised. OBJECTIVE The objective of the study was to investigate whether addition of dapagliflozin to insulin and liraglutide results in a significant reduction in glycemia and body weight. DESIGN This was a randomized clinical trial. SETTING The study was conducted at a single academic medical center. PARTICIPANTS Participants included T1D patients on liraglutide therapy for at least last 6 months. INTERVENTION Thirty T1D patients were randomized (in 2:1 ratio) to receive either dapagliflozin 10 mg or placebo daily for 12 weeks. MAIN OUTCOME MEASURE Change in mean glycated hemoglobin after 12 weeks of dapagliflozin when compared with placebo was measured. RESULTS In the dapagliflozin group, glycated hemoglobin fell by 0.66% ± 0.08% from 7.8% ± 0.21% (P < .01 vs placebo), whereas it did not change significantly in the placebo group from 7.40% ± 0.20% to 7.30% ± 0.20%. The body weight fell by1.9 ± 0.54kg (P < .05 vs placebo). There was no additional hypoglycemia (blood glucose < 3.88 mmol/L; P = .52 vs placebo). In the dapagliflozin group, there were significant increases in the plasma concentrations of glucagon by 35% ± 13% (P < .05), hormone-sensitive lipase by 29% ± 11% (P < .05), free fatty acids by 74% ± 32% (P < .05), acetoacetate by 67% ± 34% (P < .05), and β-hydroxybutyrate by 254% ± 81% (P < .05). Urinary ketone levels also increased significantly (P < .05). None of these changes was observed in the placebo group. Two patients in the dapagliflozin group developed diabetic ketoacidosis. CONCLUSIONS Addition of dapagliflozin to insulin and liraglutide in patients with T1D results in a significant improvement in glycemia and weight loss while increasing ketosis. If it is decided to use this approach, then it must be used only by a knowledgeable patient along with an endocrinologist who is well versed with it.