ORIGINAL ARTICLE Effects of Liraglutide, a Human Glucagon-like Peptide-1 Analogue, on Body Weight, Body Fat Area and Body Fat-related Markers in Patients with Type 2 Diabetes Mellitus Daisuke Suzuki, Masao Toyoda, Moritugu Kimura, Masaaki Miyauchi, Naoyuki Yamamoto, Hiroki Sato, Eitaro Tanaka, Yusuke Kuriyama, Han Miyatake, Makiko Abe, Tomoya Umezono and Masafumi Fukagawa Abstract Objective To evaluate the effects of six-month liraglutide treatment on body weight, visceral and subcutaneous fat and related markers in Japanese type 2 diabetic patients. Methods A total of 59 patients with type 2 diabetes were treated with liraglutide (0.3 mg/day for 1 week andthen0.6mg/dayfor 1 week, gradually increasing the dose to 0.9 mg/day) for six months. Changes in body weight, body mass index (BMI), HbA1c, the fasting blood glucose level, visceral and subcutaneous fat areas, hepatic and renal CT values and the associated markers proinsulin, adiponectin and pentraxin (PTX) 3 were measured. Results The study included one treatment-naïve patient, 10 patients who were switched from oral antidiabetic drugs and 35 patients who were switched from insulin therapy. At six months after treatment, the preprandial blood glucose levels were higher (148.8±40.5 mg/dl) than the baseline values (130.8±36.7, p< 0.05); however, body weight, BMI and abdominal circumference were lower, and the liver/kidney CT ratio improved significantly from 1.64±0.44 at baseline to 1.78±0.42. An analysis of the patients who were not pretreated with insulin resistance ameliorators showed that six months of liraglutide treatment significantly decreased the subcutaneous but not visceral fat areas, significantly decreased the serum adiponectin levels and significantly increased the serum PTX3 levels. Conclusion In addition to its glucose-lowering effects, liraglutide exhibits weight loss promotion actions, reducing subcutaneous fat areas in particular. The weight and total fat area reduction properties of liraglutide are likely to be beneficial when this medication is used in combination with other oral antidiabetic drugs and insulin. Key words: human GLP-1 analogue, type 2 diabetes, BMI (Intern Med 52: 1029-1034, 2013) () Introduction Type 2 diabetes is a metabolic disease characterized by chronic hyperglycemia. The key to successfully treating diabetes is controlling the blood glucose levels and other metabolic parameters and preventing the development of cardiovascular disease, neuropathy, retinopathy and nephropathy. A broad range of drugs are currently available for the treatment of type 2 diabetes, primarily comprising promoters of insulin secretion and ameliorators of insulin resistance (sensitivity enhancers). However, the use of intensified treatment to maintain adequate blood glucose control can result in undesirable weight gain, even with strict adherence to dietary Division of Nephrology, Endocrinology and Metabolism, Department of Internal Medicine, Tokai University School of Medicine, Japan Received for publication September 13, 2012; Accepted for publication January 27, 2013 Correspondence to Dr. Daisuke Suzuki, daisuke@is.icc.u-tokai.ac.jp 1029
and exercise therapies (1). Obesity and weight gain in patients with type 2 diabetes not only adversely influence blood glucose control, but also serve as independent risk factors for cardiovascular disease. Therefore, in the treatment of type 2 diabetes, preventing weight gain is of paramount importance from the viewpoint of the long-term prognosis (2). While the primary feature of type 2 diabetes in Caucasians is insulin resistance, in Asians, including Japanese, insulin hyposecretion is the norm (3). In addition, a tendency toward obesity is typical in Caucasian diabetics, whose mean body mass index (BMI) often exceeds 30, unlike that observed in Asians (3). Recent trends show an increase in the percentage of diabetics who are obese in Japan; thus, preventing weight gain is becoming increasingly important in this group of patients. Glucagon-like peptide-1 (GLP-1) is a gastrointestinal 29-30 amino acid peptide hormone secreted by L cells in the lower part of the small intestine (4). Several basic and clinical studies have shown that GLP-1 exhibits blood glucoselowering actions based on its promotion of glucosedependent insulin secretion and weight-loss actions based on its suppression of both appetite and gastrointestinal peristaltic movement. Experimental studies have defined a broad range of other bioactivities of this hormone. Although several studies have shown the utility of GLP-1 in the treatment of type 2 diabetes, the protein undergoes rapid degradation by dipeptidyl peptidase-4 (DPP-4) within the body, thus necessitating continuous subcutaneous injection to realize its clinical application (4). The human GLP-1 analogue, liraglutide, is a glucose-lowering agent with a prolonged action of GLP-1 that is achieved through the addition of fatty acids, thereby increasing its affinity for blood albumin and allowing for once-daily subcutaneous injection. The drug has been available clinically in Japan since June 2010 (5). Clinical studies conducted in Japan and overseas have shown the effectiveness of liraglutide monotherapy for weight loss (6-10). In addition, one study found that treatment with liraglutide reduces both visceral and subcutaneous fat areas (6). While these findings emphasize the importance of suppressing weight gain in the treatment of type 2 diabetes, the only class of currently available clinically applicable drugs that induce weight loss are GLP-1 receptor agonists, including liraglutide. In Japanese patients with type 2 diabetes, however, the effects of the drug on body weight and visceral and subcutaneous fat in actual clinical settings remain unclear. Based on this background, in this retrospective study, we examined the effects of six-month liraglutide treatment on both the body weight and visceral and subcutaneous fat areas. Materials and Methods The study population comprised 59 patients with type 2 diabetes who began liraglutide treatment at the Outpatient Clinic of Tokai University Hospital between June 2010 and June 2011. The study was approved by the Institutional Review Board for Clinical Research, Tokai University, and all patients gave their informed consent to participate in this study. The therapeutic regimen used for the administration of liraglutide consisted of the following: After a washout period to remove pretreatment drugs (other than sulfonylureas), liraglutide was administered at an initial dose of 0.3 mg/day for at least one week and then at 0.6 mg/day for another week or longer, with stepwise increases in the dose up to 0.9 mg/day, excluding patients who developed severe gastrointestinal symptoms. Only sulfonylureas were permitted as concomitant medications, in compliance with the current requirements for their dosage and administration in Japan. Judgment on the continuation/discontinuation of liraglutide treatment was made by the attending physician. Body weight, BMI, hemoglobin A1c (HbA1c), fasting blood glucose (FBG) and preprandial blood glucose (PBG) were measured by self-monitoring of a blood glucose (SMBG) system, and systolic and diastolic blood pressures, visceral and subcutaneous fat areas and hepatic and renal CT values were measured at baseline and after liraglutide therapy. The visceral and subcutaneous fat areas were determined using subperitoneal and intraperitoneal CT scans, with the fat density determined according to pixel gradations. The ratio of the CT value of the liver to that of the kidney was used as an index of fatty liver. The serum levels of proinsulin (a marker of abnormal insulin secretion from pancreatic β cells, serving as an index of the pancreatic β cell function (11)), high-molecular weight adiponectin (an index of insulin resistance whose level correlates inversely with the visceral fat area (12)) and pentraxin 3 (PTX3, a marker of inflammatory cardiovascular disease (13)) were determined. The HbA1c levels were measured using highperformance liquid chromatography and expressed as National Glycohemoglobin Standardization Program (NGSP) values. The results are shown as the mean ± SD. Differences between the baseline and post-liraglutide treatment values were tested for statistical significance using the paired t-test. A p value of <5% was considered to be statistically significant. Results Of the 59 subjects, 13 discontinued liraglutide treatment after 12±11 weeks due to the appearance of side effects. The remaining 46 patients (age 58.6±10.5 years; HbA1c: 7.9±1.2%) comprised the analysis set. Of these, one patient was naïve to antidiabetic drugs, 10 patients were switched from other oral diabetes drugs and 35 patients were switched from insulin therapy. The daily insulin dose was 19.6±19.0 U/day (minimum: 14 U/day, maximum: 102 U/ day). For the 46 patient-study group, the baseline measurements revealed a BMI of 29.7±6.3 kg/m 2 and systolic and diastolic blood pressures of 126.1±14.8 and 76.9±13.6 mmhg, respectively (Table 1). The fasting blood insulin and fasting 1030
Table 1. Clinical Characteristics and Effects of 6-month Treatment with Liraglutide in 46 Patients baseline after treatment p value Age (years) 58.6±10.5 - Males/females 28/18 - Height (m) 1.64±0.11 - Number of patients on insulin therapy 35 - Number of patients on oral medications 10 - Number of drug-naïve subjects 1 - Body weight (kg) 80.8±23.2 78.0±19.8 0.0002 BMI (kg/m 2 ) 29.7±6.3 28.8±5.2 0.0002 SPB (mmhg) 126.1±14.8 125.9±11.5 NS DBP (mmhg) 76.9±13.6 75.1±12.2 NS FBG (mg/dl) 141.6±32.6 148.4±51.1 NS PBG (mg/dl) 130.8±36.7 148.8±40.5 0.0041 HbA1c (%) 7.9±1.2 7.6±1.5 NS IRI (μu/ml) 12.3±11.0 13.8±12.9 NS CPR (ng/ml) 2.24±1.44 2.46±1.29 NS Human proinsulin (pmol/l) 28.9±28.6 25.7±23.7 NS High-molecular weight adiponectin (μg/ml) 4.5±3.6 3.4±2.6 0.0002 PTX3 (ng/ml) 1.49±0.47 1.84±0.74 <0.0001 HOMA-IR 3.8±3.1 4.3±2.9 NS HOMA- 65.1±38.0 61.4±45.7 NS Visceral fat area (cm 2 ) 167±81.4 157±73.9 0.0297 Subcutaneous fat area (cm 2 ) 250±133 218±111 <0.0001 Visceral to subcutaneous fat ratio (%) 40.0±9.5 42.4±10.4 0.0029 Abdominal circumference (cm) 96.4±15.2 93.6±14.1 0.0002 Data are expressed as mean±sd. SBP: systolic blood pressure, DBP: diastolic blood pressure, FBG: fasting blood glucose, PBG: pre-prandial blood glucose, IRI: immunoreactive insulin, CPR: C-peptide immunoreactivity, PTX3: pentraxin 3, HOMA-IR: homeostasis model assessment of insulin resistance, NS: not significant blood C-peptide immunoreactivity (CPR) levels at baseline were 12.3±11.0 and 2.24±1.44 ng/ml, respectively (both within the normal ranges). However, the blood proinsulin level was 28.9±28.6, which was higher than the upper limit of the reference value, and excess insulin secretion due to obesity was suspected. The levels of high-molecular weight adiponectin and PTX3 at baseline were within the normal ranges. The visceral fat area was 167±81.4 cm 2, which was far greater than the 100 cm 2 cutoff level for metabolic syndrome (14) (Table 1). We also measured the same variables after the six-month treatment period. The HbA1c level improved to 7.6±1.5%; however, the change was not statistically significant. The PBG level increased significantly from a baseline value of 130.8±36.7 to 148.4±40.5 mg/dl. Significant improvements were also noted in both body weight (baseline: 80.8±23.2, after treatment: 78.0±19.8 kg) and BMI (baseline: 29.7±6.3, after treatment: 28.8±5.2 kg/m 2 ). The six-month liraglutide treatment had no significant effects on systolic blood pressure, diastolic blood pressure or the FBG level. With regard to markers of pancreatic β cells, liraglutide treatment had no significant effects on the fasting blood insulin, fasting blood CPR or the proinsulin level. Liraglutide therapy resulted in slight but significant reductions in the visceral fat area to 157±73.9 cm 2 and the subcutaneous fat area to 218±111 cm 2, with a significant increase in the visceral to subcutaneous fat ratio (baseline: 40.0, after treatment: 42.4). Furthermore, the abdominal circumference measured with a tape measure during exhalation decreased significantly from a baseline value of 96.4±15.2 to 93.6± 14.1 cm after treatment (Table 1). Nine patients (including one who discontinued liraglutide treatment) treated with an insulin resistance ameliorator (pioglitazone) as a pretreatment drug were separated from the analysis due to the possible effects of such treatment on body fat, the liver/kidney CT ratio, the high-molecular weight adiponectin level and HOMA-IR (Table 2). The HbA1c level improved significantly in this group from 7.9± 1.2 to 7.4±1.4%, and the PBG level rose significantly from 130.4±35.9 at baseline to 142.8±37.0 mg/dl at the end of the six-month liraglutide therapy. Significant changes were observed in body weight and BMI, while systolic blood pressure, diastolic blood pressure and the FBG level were not significantly different in the non-pioglitazone group. The liver/kidney CT ratio (an index of fatty liver), improved significantly from the baseline value of 1.64±0.44 to 1.78±0.42 after treatment (Table 2). Finally, liraglutide treatment significantly decreased the subcutaneous fat area and abdominal circumference but had no effect on the visceral fat area. In the same group of 38 patients, liraglutide significantly decreased the high-molecular weight adiponectin level (baseline: 4.1±2.8, after treatment: 3.6±2.8 μg/ml) and significantly increased the PTX3 level (baseline: 1.54±0.49, after treatment: 1.82±0.70 ng/ml) (Table 2). Discussion Liraglutide, a human GLP-1 analogue, was approved in 1031
Table 2. Effects of 6-month Treatment with Liraglutide in Pioglitazone Group and Nonpioglitazone Group Non- Pioglitazone (n=38) Pioglitazone (n=8) baseline after treatment baseline after treatment Body weight (kg) 75.5±19.4 73.7±17.3* 105.9±24.6 96.7±20.2* BMI (kg/m 2 ) 28.1±4.8 27.6±4.2* 37.5±7.3 34.3±5.7* SPB (mmhg) 126.5±15.2 126.2±12.2 123.9±13.8 125.1±9.0 DBP (mmhg) 77.4±13.4 74.7±12.8 74.6±15.3 76.6±10.1 FBG (mg/dl) 140.4±32.9 143.2±45.0 148.6±33.4 170.0±72.5 PBG (mg/dl) 130.4±35.9 142.8±37.0* 133.0±46.2 211.0±11.4 HbA1c (%) 7.9±1.2 7.4±1.4* 7.9±1.0 8.1±1.7 IRI (mu/ml) 9.6±6.2 11.5±7.5 26.7±19.2 24.4±24.1 CPR (ng/ml) 2.01±1.17 2.38±1.35 3.44±2.29 2.85±0.99 Human proinsulin (pmol/l) 26.9±28.2 25.4±25.9 38.7±30.8 27.1±10.4 High-molecular weight adiponectin (mg/ml) 4.1±2.8 3.6±2.8* 6.5±6.1 2.4±1.2* PTX3 (ng/ml) 1.54±0.49 1.82±0.70* 1.23±0.20 1.90±0.92* HOMA-IR 3.47±2.76 4.35±3.00 ND ND HOMA- 60.4±35.2 65.0±45.8 ND ND Visceral fat area (cm 2 ) 153.5±77.9 147.8±74.6 230.5±70.0 199.0±57.5* Subcutaneous fat area (cm 2 ) 214.2±93.4 192.7±91.2* 418.1±170.5 328.8±127.5* Visceral to subcutaneous fat ratio (%) 40.7±9.6 43.2±10.4* 36.9±9.4 39.3±10.9 Abdominal circumference (cm) 92.6±12.7 90.5±13.0* 114.4±13.6 106.9±11.3* Glutamic oxaloacetic transaminases (GOT, U/L) 24.5±11.0 26.8±10.8 53.0±26.1 40.5±16.3 Glutamic pyruvic transaminase (GPT, U/L) 28.0±17.2 29.0±15.7 53.2±26.8 39.8±23.5 GOT/GPT ratio 0.96±0.30 0.96±0.36 0.71±0.18 0.74±0.10 Liver CT 52.2±13.3 56.7±11.9* 37.2±11.4 46.1±13.3* Kidney CT 31.0±3.3 31.9±4.7 27.8±4.0 27.6±4.5 Liver/Kidney CT ratio 1.69±0.43 1.79±0.37 1.36±0.45 1.73±0.67 Data are expressed as mean±sd *p<0.05, ** p <0.001, ND: not done Abbreviations shown in Table 1. Japan in June 2010 as the first GLP-1 receptor agonist. The drug promotes insulin secretion in a glucose concentrationdependent fashion by binding to the GLP-1 receptor on pancreatic β cells. Hence, it is effective in reducing the blood glucose levels without increasing the risk of hypoglycemia (15). The additional benefits of liraglutide include the prevention of body weight gain due to its appetite- and gastrointestinal peristaltic movement-suppressing effects. Available clinical trial data have confirmed the body weight loss properties of liraglutide monotherapy (7, 10). The above characteristics support the use of liraglutide as innovative therapy for type 2 diabetes. In the present study, the weight loss effects of liraglutide were observed in an analysis of the data of the entire group of 46 patients, in spite of the lack of any glucose-lowering actions (Table 1). Of the 46 study patients, 35 switched treatment from insulin therapy to liraglutide. Since its launch, liraglutide has been used in modal switching from insulin therapy. The reasons for this practice include: 1) improved patient self-injection skills and blood glucose measurement, 2) confirmed retention of the insulin secretion capacity due to the use of insulin preparations to correct the blood glucose levels (patients encountering difficulties in eliminating glucotoxicity and achieving blood glucose control), 3) reduction in the frequency of insulin injections in some patients and 4) protection of pancreatic β cells, as reported in an animal experimental study (16), thus suggesting the expected restoration of the pancreatic β cell function. Based on the Japanese database registry of approximately 9,000 patients treated with liraglutide between June, 2010 and October, 2010, four patients developed diabetic ketoacidosis (two of whom died) and 16 suffered hyperglycemia. Of these 20 patients, 17 experienced these events after switching to liraglutide from insulin therapy. In the present study, the glucose-lowering action of liraglutide was inadequate, most likely due in part to the use of insulin pretreat- 1032
ment. However, the findings of weight loss and lower BMIs in the entire group suggest the unique utility of liraglutide, which is not found in conventional antidiabetic therapeutics. One clinical study conducted in Japan reported an improvement in the proinsulin/insulin ratio with decreased proinsulin levels (10), whereas the present study did not show any improvements in the proinsulin level. This finding also seems to be of relevance to the use of pretreatment and the insulin secretion capacity present at the time of the switch in therapeutic modality to liraglutide. Since the reported standard deviation (SD) of the proinsulin level is large and varies widely among individuals, it is difficult to assess changes in the proinsulin levels with the given sample size used to assess the blood glucose-lowering and weight-loss properties of liraglutide. Conducting a post-marketing assessment in a larger population is therefore necessary. An analysis of the changes in the visceral and subcutaneous fat areas and the serum adiponectin level showed a slight reduction the visceral fat area among the data for the entire study group (n=46). To avoid the effects of pioglitazone on the liver/kidney CT ratio, the high-molecular weight adiponectin level and HOMA-IR, we separately analyzed eight patients who were treated with pioglitazone (Table 2). Consequently, no such changes were observed in a subpopulation of subjects that did not include those treated with pioglitazone (n=38). In contrast, significant decreases in the subcutaneous fat area were observed in both groups. These results suggest that the eight patients who were treated with pioglitazone were severely obese (BMI: 37.5); therefore, switching to liraglutide was very effective for reducing the visceral fat area in these patients. Our report showed that liraglutide can change the fat distribution, including the liver/kidney CT ratio, evaluated with abdominal CT. In the LEAD-3 substudy, long-term liraglutide monotherapy significantly reduced both body weight and fat mass from baseline (17). Recent studies have demonstrated the GLP-1 receptor expression in adipocytes (18) and liver cells (19). This may explain the possible mechanisms by which liraglutide changes the fat distribution in a direct or indirect manner. The results also showed significant decreases in the highmolecular adiponectin level among the entire group of patients (n=46) and among the 38-patient subgroup. However, no significant changes in the serum high-molecular of adiponectin level were observed in the subjects with reduced visceral fat area or those with improved CT values. In this study, only three patients were treated in combination with sulfonylureas. These three patients did not affect the statistical analysis results. Since the serum adiponectin level is known to correlate inversely with the fat area (12), high levels of serum adiponectin were expected in this study; however, the opposite results were found. The results of previous animal experiments showed that liraglutide and other GLP-1 receptor agonists induce increases in the adiponectin levels and ameliorate insulin resistance associated with decreased adiponectin levels (18, 20). Another report described increases in the serum adiponectin levels after one-year treatment with a related drug, exenatide (21), in patients who had been treated with metformin alone. Based on the above findings, we believe that it is necessary to conduct another long-term prospective study of liraglutide in diabetic patients. Although the visceral fat area did not decrease significantly, a comparison of the CT values of the liver and kidneys showed decreases in these values after treatment, suggesting that the observed reduction in the pixel brightness gradient in the liver represents a reduced fat area, which could translate into an improved liver function. Significant increases in the marker for inflammatory cardiovascular disease, PTX3, were observed in this study. A recent report revealed that the plasma PTX3 protein levels exhibit a significant negative correlation with obesity indices, specifically body weight and waist circumference (22). Furthermore, these authors also reported that the PTX3 mrna levels are higher in adipocytes isolated from visceral adipose tissue than in adipocytes isolated from subcutaneous adipose tissue. In our study, we demonstrated both weight loss and increased visceral to subcutaneous fat ratios. Considered together, the significant increases in the PTX3 levels observed in our study are in agreement with the results of this previous study. In summary, treatment of Japanese type 2 diabetic patients with liraglutide not only reduced the blood glucose levels, but also resulted in weight loss, most likely due to decreased total fat areas, particularly the subcutaneous area. Liraglutide treatment seems to ameliorate fatty liver based on the finding of improved liver/kidney CT ratios. Liraglutide also decreased the serum adiponectin levels and increased the PTX3 and blood proinsulin levels. Further studies are needed to determine which patients are most suited for treatment as well as to optimize the duration of treatment. In addition, while liraglutide has been approved for use as a monotherapeutic agent and also in combination with sulfonylureas, its weight- and total fat area-lowering effects are likely to be beneficial when used in combination with other oral antidiabetic drugs and insulin. The authors state that they have no Conflict of Interest (COI). Acknowledgement We are grateful to all subjects for participating in this study and for the cooperation of the co-medical staff at Tokai University Hospital. References 1. UK Prospective Diabetes Study (UKPDS) Group. Intensive bloodglucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet 352: 837-853, 1998. 2. Lavie CJ, Milani RV, Ventura HO. Obesity and cardiovascular disease: risk factor, paradox, and impact of weight loss. J Am Coll Cardiol 53: 1925-1932, 2009. 3. Fukushima M, Suzuki H, Seino Y. Insulin secretion capacity in the 1033
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