Role of abdominal CT in predicting the diagnosis of insulin resistant diabetes abbreviated title:Diagnosing insulin resistant diabetes on abdominal CT

doi:10.4236/crcm.2013.27113

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Vol.2, No.7, 432-435 (2013) Case Reports in Clinical Medicine

http://dx.doi.org/10.4236/crcm.2013.27113

Role of abdominal CT in predicting the diagnosis of

insulin resistant diabetes abbreviated title:

Diagnosing insulin resistant diabetes on

abdominal CT

Cynthia Tan1, Aruna V ade1, Jennifer Orrico1, Julius Griauzde1, Terrence C. Demos1,

Alaleh Mazhari2, Mary Ann Emanuele2

1Departments of Radiology, Loyola University Medical Center, Maywood, USA;

Email: [email protected], [email protected], [email protected] [email protected], [email protected]

2Department of Endocrinology, Loyola University Medical Center, Maywood, USA; Email: [email protected], [email protected]

Received 26 June 2013; revised 29 July 2013; accepted 20 August 2013

cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

cited.

ABSTRACT

We report a diagnosis of diabetes type 2 sug-

gested by diffuse omental infiltration seen on

computed tomography which resolved following

treatment. There have been reports of increased

macrophage infiltration in the omental fat of dia-

betic patients which we believe is identifiable by

CT. To our knowledge, the diagnosis of diabetes

with CT has not yet been report ed. Diabe tes ty pe

2 is commonly a clinical diagnosis. However,

undiagnosed diabetic patients may present with

nonspecific manifestations and CT may be or-

dered as part of the initial evaluation. We pre-

sent a case in which diabetes type 2 was sug-

gested by diffuse omental infiltration.

Keywords: Omental Infiltration; Diabetes

1. INTRODUCTION

The obesity epidemic is increasing at an alarming rate.

Health complications from obesity have dramatically

impacted patients’ quality of life and health care. Obesity

has been strongly associated with many diseases, espe-

cially insulin resistant type 2 diabetes. Patients with dia-

betes type 2 are defined as either not producing enough

insulin or being insu lin resistant. Prior to developing type

2 diabetes, most are prediabetic as determined by ele-

vating fasting plasma glucose levels that are greater than

normal (100 mg/dl) but less than 126 mg/dl. By accu-

rately identifying patients who have not yet been diag-

nosed with diabetes, we may be able to provide early

initiation of treatment. Type 2 diabetes has been strong ly

associated with central obesity [1]. Current research has

shown preferential macrophage infiltration of omental fat

different from subcutaneous fat in Type 2 diabetic pa-

tients [2,3]. Chronic low-grade inflammation caused by

macrophage infiltration of the omentum inhibits forma-

tion of mature adipocytes alters their function [4,5].

Though much research has been done focusing on body

mass index and quantification of visceral fat by CT and

MR using volumetric assessment of visceral fat, there

has been no study addressing the alteration in visceral fat

density as shown by CT or MR imaging in patients with

insulin resistant Type 2 diabetes [6,7]. We present a pa-

tient who presented to the emergency department with

abdominal pain. Abdomen pelvis CT showed diffuse in-

filtration of omental fat and diabetes was suggested as a

possibility. Subsequ ently, the patient was proven to have

Type 2 diabetes.

2. CASE REPORT

A previously healthy 49-year-old white male pre-

sented to the emergency department with abdominal pain.

This pain had been intermittent every day for several

months and was described as needle-like with radiation

to the thighs and groin. On review of systems, the patien t

reported urinary frequency and a 20 pound weight loss

over the prior year, currently weighing 130 pounds. His

BMI was 19.8. Abdomen pelvis CT with intraveno us and

oral contrast material showed diffuse increased density

and stranding of the omentum and a 1 cm hypodense

liver lesion (Figure 1). No other abnormalities were seen.

C. Tan et al. / Case Reports in Clinical Medicine 2 (2013) 432-435

433

Based on the finding of omental fat infiltration without

any other abdominal pa thology, the possibility of Type 2

diabetes was suggested. Same day laboratory results fol-

lowing the abdominal CT revealed elevated blood glu-

cose (417 un its) and HbA1c (11.5), which were co mpati-

ble with insulin resistant diabetes (diabetes mellitus type

2). His lipid profile was normal. Autoimmune antibody

titre for glutamic acid decarboxylase, islet cell and insu-

lin antibodies was negative. Metformin (500 mg twice a

day) and glipizide (5 mg daily) were started. One month

later, follow up liver protocol CT to evaluate the liver

lesion showed no omental infiltration and a stable he-

patic hemangioma (Figure 2). Over the period of two

and a half years of treatment the patient gained 32

pounds, his blood glucose level was normal and HbA1c

level had dropped to 6.7.

3. DISCUSSION

In the US, 23.6 million adults are estimated to have

diabetes. Zhang et al. have estimated that one-fourth of

these patients remain undiagnosed. The National Health

and Nutrition Examination Survey is a random stratified

survey used to identify adults who have elevated fasting

Figure 1. Contrast enhanced axial CT scan of

the abdomen shows diffuse increased density

and stranding of the omentum (arrow).

Figure 2. Contrast enhanced axial CT scan of the

abdomen one month after treatment for diabetes

shows no omental infiltration (arrow).

plasma glucose and have never been told they have dia-

betes. The prevalen ce of undiagnosed diabetics was mul-

tiplied by the Census Bureau popu lation in 2007. Care of

known diabetics is estimated to cost $174 billion per year

in higher medical costs and lose productivity [8]. Newly

diagnosed diabetics often develop complications linked

to diabetes including retinopathy, proteinuria, neuropathy,

arterial disease, cardiovascular disease, and coronary

heart disease [8]. A claims-based study suggested costs

of diabetes begins at least 8 years prior to diagnosis [8].

Since patients with undiagnosed diabetes were omitted

from the estimated cost, the total expense of diabetes is

likely much higher [8]. Estimated national medical costs

associated with undiagnosed diabetes depend on the es-

timated prevalence and the ratio of per capita health care

used by undiagnosed diabetics [8]. Impaired glucose tol-

erance has been positively correlated with obesity [9]. In

obese patients, central adiposity shows a strong associa-

tion with obesity-related metabolic syndromes including

insulin resistant diabetes [1]. Metabo lic syndromes affect

20% - 40% of US adults and are increasing in the preva-

lence of making it a leading public health issue [10].

Type 1 diabetes mellitus occurs in young patients who

have a lack of insulin and have normal or low BMI and a

normal lipid profile [11]. Some diabetic patients have

normal or low BMI, and normal lipid profile but have

latent autoimmune diabetes (LADA) [12]. They present

at an older age than individuals with Type 1 diabetic

patients and usually need insulin after initially respond-

ing to oral medication, usually within 2 - 3 years. Type 2

diabetes mellitus typically presents at an older age and is

due to insulin resistance in addition to relative insulin

deficiency or relative impairment of insulin secretion

[13]. However, now it is being documented in younger

patients due to th e rise in obesity. Type 2 diabetes melli-

tus patients usually have elevated BMI with other co-

morbidities including hyperten sion and dyslipid emia [13].

Maturity onset diabetes of the young (MODY) is an

autosomal dominant monogenetic form of diabetes. Pa-

tients present before the age of 25 years due to a domi-

nant genetic defect [14]. These patients do not have dia-

betes autoimmu ne antibodies. Our patient was diagno sed

with Type 2 diabetes despite his normal BMI and normal

lipid profile because of his negative autoimmune anti-

body titre and negative family histo ry of MODY.

Visceral or central body fat consists of fat in the

omentum and mesentery whereas subcutaneous fat is

extraperitoneal. Visceral fat is more metabolically active

than subcutaneous fat, not only in the degree of lipolytic

activity but also in the release of adipokines. Current

research indicates that macrophage infiltration preferen-

tially into omental fat and not subcutaneous fat is exag-

gerated by central obesity and is also associated with

clinical parameters of central obesity comorbidities [2 ,3].

C. Tan et al. / Case Reports in Clinical Medicine 2 (2013) 432-435

434

It has been shown that macrophage infiltration of the

omentum induces adipose tissue inflammation that re-

sults in dysfunction of ad ipose tissue by activatin g proin-

flammatory cytokines that in turn induce insulin resis-

tance, thus linking central obesity to Type 2 diabetes.

[15].

The greater omentum is a fatty peritoneal extension

from the stomach covering intra-abdominal organs [16].

The omentum serves to contain disease processes, how-

ever, it may also contribute to disease spread [16]. The

abdominal innervation clarifies clinical findings associ-

ated with omental abnormality. The parietal peritoneum

shares its somatic innervation with the anterior abdomi-

nal musculature and skin. A diseased omentum can thus

irritate the adjacent parietal peritoneum due to its close

proximity as well as its mobility. The anterio r abdominal

wall can therefore be the site of localized or diffuse ten-

derness, rigidity, and guarding. These nonspecific signs

and symptoms can mimic more ominous diseases such as

appendicitis, diverticulitis, peptic ulcer disease, chole-

cystitis, and pancreatitis. Omental infiltration is a non-

specific finding seen with diseased omentum and is as-

sociated with multiple etiologies including peritoneal

carcinomatosis, tuberculosis peritonitis, malignant peri-

toneal mesothelioma, pseudomyxoma peritonei, lym-

phomatosis, and cirrhosis with portal hypertension. Other

conditions which can demonstrate omental infiltration

include omental infarction, granuloma, hematoma, and

hernia. In cases where no etiology can be identified, as in

our patient, the diagnosis is idiopathic omental infiltra-

tion.

The evaluation of omental processes is primarily by

CT [16]. Approximately 10% of the population are esti-

mated to obtain a CT study during their lifetime, and a

total of 75 million scans are performed annually [17].

Currently, the utilization of CT to identify or follow up

idiopathic diffuse omental infiltration is not done. The

patient presented here had diffuse omental infiltration

indicated by the increased density of the omental fat

compared to subcutaneous fat. No underlying etiology

was found for this infiltration. Upon treatment for diabe-

tes with metformin and glipizide for one month, the

omental fat density returned to normal. He has responded

well to this treatment and has no t required insulin so far.

The CT finding o f diffuse omental infiltration with no

etiology should raise su spicion of insulin resistant diabe-

tes even in patients with normal or low BMI and normal

lipid profile. This can lead to earlier diagnosis and treat-

ment with reduction of comorbidities.

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