Effect of Liraglutide on Clock Genes

Background: Cumulative evidence strongly implicates that the disruption of clock genes (CGs) plays a causative role in insulin resistance, hyperglycemia and β-cell dysfunction in type 2 diabetes (T2D). CGs are synchronized by meal timing. Indeed, in animals and patients with T2D, restricting feeding to specific hours, such as large meals assigned to breakfast with reduced dinner, can reset and restore CG expression, resulting in improved glycemic control, insulin sensitivity and reduction of HbA1c compared to isocaloric diet with a different meal timing (small breakfast and overeating at dinner). Since glucagon-like peptide-1 (GLP-1) is secreted within a few minutes in response to food ingestion and it influences multiple humoral and neural signaling pathways that may further influence CG expression in many cells, it has been suggested that GLP-1 may be a resetting signal for the CGs, synchronizing the food entrainment on CGs expression thereby influencing the glucose metabolism. In fact, several studies in animal models, documented that GLP-1 analogs either exenatide or liraglutide, via activation of CG expression and AMPK-SIRT-1 pathway, improved insulin sensitivity, muscular glucose uptake, reduced hepatic and cardiac steatosis, inflammatory cytokines and oxidative stress, and enhanced β-cell insulin secretion and proliferation, independently of the GLP-1 analog glucose-lowering effects.

To the best of the investigators knowledge, no systemic study in humans to date has investigated the changes in the expression of CGs and AMPK-SIRT-1 pathway, concomitantly with the effect on glycemic control, insulin sensitivity, beta cell function, and inflammatory cytokines in T2D individuals during treatment with Liraglutide or other GLP-1 analogs.

Hypothesis: The investigators hypothesize, that Liraglutide, by enhancing CG and AMPK-SIRT-1 expression may reverse the metabolic abnormalities of T2D, improving insulin sensitivity, overall glycemic excursion, inflammatory cytokines and β-cell function in T2D individuals.

Objectives:

The investigators aim is to compare the effect of 40 days treatment with Liraglutide (LIR) vs. 40 days with placebo (PLA) in T2D participants on the following end points:

Primary end-points:

• Change in the oscillation of CG (i.e. CLOCK, BMAL1, Per1, Per2, Cry1, Cry2, Rev-erb-alpha, Ror-alpha), AMPK, SIRT1 and inflammatory cytokines mRNA expression in white blood cells (WBCs).

Secondary end-points:

• Overall daily glycemic variation assessed with continuous glucose monitoring system (CBMS)
• Serum levels of inflammatory cytokines (TNF-α, IL-1β, IL-6)
• β-Cell function derived from glucose and insulin response to OGTT

Methods: In a randomized, double blind crossover-within-subject clinical trial, the investigators will study 18 weight- matched obese and overweight participants with known T2D, diagnosed < 20 years, and HbA1c 7.0 to 10 %, BMI: 26-32 kg/m2 treated with diet alone or diet plus metformin, and sodium/glucose cotransporter 2 (SGLT2) inhibitors (gliflozins).

All 18 T2D participant will undergo randomization at baseline to two 40 days treatment periods, either starting with LIR treatment, and then after 2 weeks of wash-out, will crossover to second treatment period of 40 days with PLA, or vice-versa, starting the first period with PLA during 40 days and then crossover to 40 days with LIR. The treatment with LIR and PLA will be up-titrated progressively from 0.1ml to 0.3ml to avoid the secondary effects of LIR.

Expected results: The investigators expect that LIR will lead to enhanced expression of the diurnal oscillation of the CGs and AMPK, SIRT1 pathway, will reduce serum inflammatory cytokines, and overall daily glycemic variation while improving insulin sensitivity and β-Cell function.

Significance of the study: Showing that GLP-1 analog Liraglutide, improves β-cell function in type 2 diabetic individuals, by enhancing clock genes mRNA expression and the AMPK-SRIT1 pathway, may change the approach of Liraglutide treatment, from being an excellent anti-diabetic agent with beneficial effect on the diabetic heart, to a drug with the ability to synchronize body metabolism and improve glucose homeostasis in health and disease. Presently, there are many available drugs for the treatment of type 2 diabetes, but their mode of action does not make any of them more advantageous. If this GLP-1 analog not only reduces glucose, body weight and cardiovascular risk, but also synchronizes the circadian clock, this would make of Liraglutide the drug of choice (immediately after metformin) for the treatment of obesity, early diabetes and for prevention of T2D complications and cardiovascular events in high risk patients, moreover, Liraglutide by influencing clock genes expression, may further prevent several other age related disorders linked to the disruption of clock genes.