¹Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.

Corresponding Author: Yoshifumi Saisho, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan, Tel:+81-3-3353-1211; E-Mail: [email protected]

Received Date: 31 Jul 2017    Accepted Date: 01 Aug 2017   Published Date: 02 Aug 2017

Copyright © 2017 Saisho Y

Citation: Saisho Y and Murakami R. (2017). Pancreas Fat and Diabetes. Mathews J  Diabetes Obes. 2(2): 008.

Obesity is an important factor for the development of diabetes. When excess of calorie intake continues for a long time, fat supply exceeds the capacity of subcutaneous fat storage in the body. Then spillover of fat leads to ectopic fat deposits in various tissues such as the liver, heart, skeletal muscle, and pancreas as well [1].

In Zucker Diabetic Fatty (ZDF) rats, beta cell dysfunction and apoptosis were accompanied by excess lipid accumulation in islets [2], suggesting that beta cell apoptosis is induced by ectopic fat deposits in the pancreas, so called lipotoxicity hypothesis. However, clinical meaning of pancreas fat in humans remains unclear. In humans, many reports regarding pancreas fat have been published, but results are inconsistent. We suppose that one of the reasons for these inconsistent results is due to the intricate structure of the pancreas, since it is difficult to distinguish intra-pancreas fat from fat tissue outside the pancreas by computed tomography (CT) or magnetic resonance imaging (MRI) studies.

Previous reports including imaging and histological assessments showed that pancreatic fat content is significantly increased with obesity [3-5] and age [5, 6]. But recent systematic review by Singh et al. showed conflicting results that presence of non-alcoholic fatty pancreas is independent of age and BMI [7].

It is also controversial whether pancreas fat is associated with diabetes. First, Tushuizen et al. reported that pancreatic fat content was associated with decreased beta cell function in non-diabetic subjects by using magnetic resonance spectroscopy (MRS) [8]. Whereas recent systematic review showed that pancreas fat was associated with risks of diabetes and metabolic syndrome [7], there was no significant difference in pancreas fat between subjects with and without diabetes in our previous report using CT imaging [6]. A recent study in which pancreatic intralobular fat was measured carefully by using MRI/MRS also showed no association between pancreatic fat and diabetes [9].

Aimed at accurate measurement of intra-pancreas fat, we recently reported the intra-pancreas fat content assessed by using autopsy and surgical specimens [10]. Our study was a relatively large-scale study including autopsy from 72 Japanese non-diabetic adults and pancreas samples from 99 diabetic and non-diabetic adults who underwent pancreatic surgery. We reported that pancreas fat was significantly associated with age and BMI. And there was no significant difference in intra-pancreas fat between subjects with and without diabetes. No correlation was found between the pancreas fat and beta cell mass.

Our findings suggest that pancreatic fat deposits have little effects on beta cell mass and development of diabetes in humans. Although there have been a number of reports regarding pancreas fat in humans assessed by CT or MRI/MRS imaging, more careful and accurate measurement of the pancreas fat will be warranted in future studies.

REFERENCES

1. Sattar N and Gill JM. (2014). Type 2 diabetes as a disease of ectopic fat?. BMC Med. 12: 123.
2. Lee Y, Hirose H, Ohneda M, Johnson JH, et al. (1994). Beta-cell lipotoxicity in the pathogenesis of non-insulindependent diabetes mellitus of obese rats: impairment in adipocyte-beta-cell relationships. Proc Natl Acad Sci U S A. 91(23): 10878-10882.
3. Lingvay I, Esser V, Legendre JL, Price AL, et al. (2009). Noninvasive quantification of pancreatic fat in humans. J Clin Endocrinol Metab. 94(10): 4070-4076
4. Lee JS, Kim SH, Jun DW, Han JH, et al. (2009).Clinical implications of fatty pancreas: correlations between fatty pancreas and metabolic syndrome. World J Gastroenterol. 15(15): 1869-1875.
5. Olsen TS. (1978). Lipomatosis of the pancreas in autopsy material and its relation to age and overweight. Acta Pathol Microbiol Scand A. 86A(5): 367-373
6. Saisho Y, Butler AE, Meier JJ, Monchamp T, et al. (2007). Pancreas volumes in humans from birth to age one hundred taking into account sex, obesity, and presence of type-2 diabetes. Clin Anat. 20(8): 933-942
7. Singh RG, Yoon HD, Wu LM, Lu J, et al. (2017). Ectopic fat accumulation in the pancreas and its clinical relevance: A systematic review, meta-analysis, and meta-regression. Metabolism. 69: 1-13.
8. Tushuizen ME, Bunck MC, Pouwels PJ, Bontemps S, et al. (2007). Pancreatic fat content and beta-cell function in men with and without type 2 diabetes. Diabetes Care. 30(11): 2916-2921.
9. Begovatz P, Koliaki C, Weber K, Strassburger K, et al. (2015). Pancreatic adipose tissue infiltration, parenchymal steatosis and beta cell function in humans. Diabetologia. 58(7): 1646-1655.
10. . Murakami R, Saisho Y, Watanabe Y, Inaishi J, et al. (2017). Pancreas fat and beta cell mass in humans with and without diabetes: An analysis in the Japanese population. J Clin Endocrinol Metab.