NAFLD is characterized by fatty infiltration of the liver, mostly in the form of triglycerides, which exceeds 5% of the liver weight. NAFLD is histologically similar to alcoholic liver disease, but by definition it occurs in the absence of excessive alcohol consumption and is not due to other identifiable causes of fatty liver such as hepatitis C and certain medications [1].

NAFLD represents a spectrum of clinical–pathological features ranging from simple steatosis, which is characterized by fatty infiltration only, to non-alcoholic steatohepatitis (NASH), which is characterized by inflammation and hepatocellular injury with or without fibrosis and cirrhosis [1,2]. Most people with NAFLD have an increase in liver fat content alone, which is apparently benign; others develop NASH that can progress to cirrhosis. The diagnosis of NAFLD is typically suspected in asymptomatic patients who are found to have elevated aminotransferase levels and/or ultrasonic evidence of fatty liver [3].

Diabetes mellitus is one of the most common metabolic disorders and leading cause of death and disability in the world. There is a strong relationship between hepatic triglyceride content and insulin resistance [4]. NAFLD is associated with insulin resistance [5,6]. It appears to be both a cause and a consequence of insulin resistance. A mechanism by which hepatic steatosis causes insulin resistance involves an inhibition of insulin signaling at the level of the insulin receptor [7].

Insulin resistance impairs the suppression of lipolysis, and this leads to an increased release of free fatty acids from adipose tissue so that more are delivered to and taken up by the liver [8,9]. This excess amount of free fatty acids can overload the hepatic mitochondrial beta oxidation system, the major pathway of fatty acid oxidation in the liver, leading to the accumulation of fatty acids in the liver [10]. In the majority of patients, simple steatosis-the accumulation of fat in the liver-follows a relatively benign course [11]. It can be present for decades without leading to more serious liver damage [12]. However, it may evolve into NASH, which is a more aggressive liver disease that tends to be progressive and may lead to cirrhosis [3,11].

Aims and objectives

To describe the frequency of undiagnosed diabetes mellitus in patients of nonalcoholic fatty liver disease at IGMC Shimla.

• Study Design: Hospital based observational cross-sectional study at IGMC Shimla

• Study Period: November 2017 to November 2018

• Setting: Department of Medicine and Radiology, IGMC Shimla

Methodology

Patients fulfilling the inclusion criteria were selected. A detailed informed consent was taken from all the participants. Demographic profile recorded and detailed history with examination was done in all the patients as per the proforma attached. Analysis of symptoms was done along with underlying co- morbid conditions and drugs used. Anthropometric data, such as body mass index (BMI) and blood pressure were measured. 

Serological tests for HBsAg, anti-HCV, Aspartate aminotransferase, Alanine aminotransferase, total bilirubin, lipid profile, FBG, RBG and HbA1C (by TOSOH- tm Bioscience Haemoglobin A1c Cotrol for G8 automated HPLC Analyser) were done. 

Diagnosis of diabetes was made on the basis of American Diabetes Association criteria. Patients with BMI of more than 23kg/m2 were labeled as overweight and those with BMI of more than 25kg/m2 were labeled as obese (Asian standards). Diagnosis of fatty liver was made on the basis of ultrasound. 

Patients diagnosed with any medical conditions other than diabetes were provided consultation from concerned departments. Ethical approval was taken from the ethical committee of IGMC Shimla. 

Inclusion Criteria

• Who consented to be part of study

• Age more than 18 years

• All patients diagnosed as NAFLD by abdominal ultrasonography

Exclusion Criteria

• Patients less than 18 years

• Patients with history of alcohol intake more than 20 grams/day in males and more than 10 grams/day in females 

• Known diabetic patients

• Patients with positive viral markers for hepatitis B and hepatitis C

• Patients taking drugs causing liver fat accumulation

• Patients not giving consent

Defining Criteria for Fatty Liver 

(Based on Diagnostic Ultrasound by Carol M. Rumack)

Mild: Minimal diffuse increase in hepatic echogenicity with normal visualization of diaphragm and intrahepatic vessel borders. 

Moderate

Moderate diffuse increase in hepatic echogenicity with slightly impaired visualization of diaphragm and intrahepatic vessels. 

Severe

Marked increase in echogenicity with poor penetration of posterior segment of right lobe of liver and poor or no visualization of hepatic vessels and diaphragm. 

Defining criteria for diabetes mellitus (based on American Diabetes Association) 

• Symptoms of diabetes plus random blood glucose concentration =/> 200mg/dl. and/or 

• Fasting blood glucose=/>126mg/dl. Fasting defined as no caloric intake for at least 8 hours. and/or 

• HbA1C =/>6.5%. and/or 

• 2-h plasma glucose=/>200mg/dl during an oral glucose tolerance test

Statistical Analysis 

Data was entered on MS Excel spreadsheet. Results were summarized in tables and percentages. Quantitative data was summarized using means +/- & standard deviation. Cross tabulation with outcome variable of interest was done using statistical SPSS software version 22.0.0.0.

Total of 100 cases, ultrasonographically diagnosed as NAFLD were included in this study. Mean age of the cases was 51.59±11.44 years. Mean age in males was 51.13±11.12 years while in female it was 51.73±11.60 years. Maximum number of patients was in 4th and 5th decades. Out of 100 total patients, total males were 23 and females were 77. Male: female ratio was 1:3.

On physical examination mean BMI (Kg/m2) was 25.11±3.34, mean systolic blood pressure (mm of Hg) was 115.76±10.90, mean diastolic blood pressure (mm of Hg) was 78.40±5.97. The mean fasting blood glucose (mg/dl) was 116.59±73.64, mean HbAIC was 7.31±13.48. Mean serum cholesterol (mg/dl) was 192±28.27, mean serum triglyceride (mg/dl) was 169.729±1.01, mean serum HDL (mg/dl) was 40.786±.36 and mean serum LDL (mg/dl) was 111.86±28.79. Mean AST (u/l) was 47.422±0.97, mean ALT (u/l) were 49.542±5.05 (Table 1).

According to BMI, 1patient (1%) was underweight, 22(22%) were normal, 36(36%) patients were overweight and 41(41%) patients were obese (Table 2). 13(13%) patients were hypertensive. 14(14%) patients had diabetes mellitus. Out of 14 total diabetic patients, 85.71% were females and 14.28% were males Impaired fasting glucose were found in 45(45%) of patients. Increased serum Cholesterol level was seen in 46(46%) patients. Increased serum triglyceride level was seen in 60(60%) patients. Low serum HDL level was seen in 88% patients. Increased serum LDL levels were 31% of patients. ALT and AST levels were elevated in 56% and 58% of patients. Total of 100 cases, 54%, 42% and 4% of cases had grade I, II, and III fatty liver respectively (Table 2).

Percentage of diabetic patients increased as grade of fatty liver increased i.e. 9.30%, 14.30% and 75% in grade I, II, III respectively. All grade III fatty liver patients had increased triglyceride level i.e. 4(100%) while 32 (76.2%) of grade II and 24(44.4%) of grade I patients were having increased triglyceride levels (Table 3).

In patients of T2DM with NAFLD 6(42.9%), 13(92.90%), 10(71.4%), 14(100%) had hypertension, hypertriglyceridemia, increased levels of LDL, increased BMI respectively. On statistical analysis, there was positive correlation of diabetes mellitus, increased triglyceride level with grade of fatty liver. There was also positive relation between T2DM and hypertension, dyslipidemia, increased body mass index. NAFLD patients with diabetes mellitus had increased prevalence of various components of metabolic syndrome. 

In patients of NAFLD with diabetes mellitus 6(42.9%) had hypertension while in patients of NAFLD patients without diabetes mellitus 7(8.1%) had hypertension and this observation was statistically significant. In patients of NAFLD with diabetes mellitus 13(92.90%) had hypertriglyceridemia while in patients of NAFLD patients without diabetes mellitus 47(54.7%) had hypertriglyceridemia and this observation was statistically significant. In patients of NAFLD with diabetes mellitus 10(71.4%) had increased levels of LDL while in patients of NAFLD patients without diabetes mellitus 21(24.4%) had increased levels of LDL and this observation was also statistically significant. 

In patients of NAFLD with diabetes mellitus 14(100%) had increased BMI while in patients of NAFLD patients without diabetes mellitus 63(73.3%) had increased BMI. Although difference was quite large but this observation was not statistically significant. 92.9% of NAFLD patients with diabetes mellitus had low HDL level, while 87.2% of NAFLD patients without diabetes mellitus had low HDL. This observation was not statistically significant (Table 4).

Table 1: Mean and SD of various variables

Table 2: frequency of various variables.

Table 3: Diabetes and TG In relation to grade of fatty liver

Table 4: Association of various variables with NAFLD.

In our study, 14 (14%) of NAFLD patients had diabetes mellitus according to American Diabetes Association criteria for diabetes mellitus. Duseja et al. [13] (13%) and Madan et al. [14] (10%) have had similar findings. Impaired fasting glucose was found in 45(45%) patients. Gaharwar et al. [15] (45.71%) also had similar findings. 72.4% and 28% patients had impaired fasting glucose as reported by Duseja et al. [13] and Bajaj et al. [16] respectively. 

14% of our patients had diabetes, while another 45% had impaired fasting glucose. A lower prevalence of diabetes (7%–22%) was also found in other Indian studies [13,14]. This is in contrast to western figures-38% cases of diabetes in NAFLD (UK) [17], while among Americans, diabetes was associated with half of the histologically proven patients with NAFLD [18]. 

In our study 13(13%) patients were hypertensive. In the study of Duseja et al. [13] (13%) and Madan et al. [14] (10%), they had similar findings. In our study increased serum triglyceride level was seen in 60(60%) patients. In a study by Gaharwar et al. [15] (67.14%), they also had similar findings.

In our study, it was observed that the percentage of diabetic patients increased as grades of fatty liver increased i.e. 9.30%, 14.30% and 75% in grade I, II, III respectively were diabetics. All grade III fatty liver patients had increased triglyceride level i.e. 4(100%) while 32 (76.2%) of grade II and 24(44.4%) of grade I patients were having increased triglyceride levels and this observation was statistically significant. 

In our study 88(88%) patients had low HDL levels (<40 mg/dl in males and <50 mg/dl in females) with a mean of 40.78 ± 6.36 mg/dl as compared to 66.7% described by Bajaj et al. Gaharwar et al. [15,16] (94%) also had similar findings. In our study, it was observed that 92.9% of NAFLD patients with diabetes mellitus had low HDL levels, while 87.2% of NAFLD patients without diabetes mellitus had low HDL levels. This observation was not statistically significant. 

In our study, the mean serum TG and mean serum Cholesterol levels were above the normal upper limit, while the mean serum HDL level was below the normal limit, signifying that most patients had dyslipidemia, which is a known risk factor for fatty liver. 

In our study, the mean BMI was 25.113±.34; while 36% and 41% of patients were overweight and obese, respectively. Similar findings were seen in most other Indian studies with a median BMI value of 26.7 kg/m2 with almost 60%–70% patients having obesity as defined by the Asia-Pacific criteria [13,14]. An exception to this was a study done in Bengal by Das et al. [19] with very low BMI (22.73±.90 kg/m2) this may be because the study was carried out in an extremely underprivileged area; and as expected, the prevalence of NAFLD was only 8.7%. The Bengal findings cannot be applied to other populations. Our patients with NAFLD had a lower mean value of BMI as compared to the western figures (30–38 kg/m2) [20,21] Despite lower BMI, our patients had fatty liver, possibly due to characteristics of South Asian phenotype (i.e. greater propensity to IR and central obesity) [22]^. 

In our study, the patients of NAFLD with diabetes mellitus 6(42.9%) had hypertension while in patients of NAFLD patients without diabetes mellitus 7(8.1%) had hypertension and this observation was statistically significant (OR=8.46, 95%CI=2.28-31.39, P=0.003). In patients of NAFLD with diabetes mellitus 13(92.90%) had hypertriglyceridemia while in patients of NAFLD patients without diabetes mellitus 47(54.7%) had hypertriglyceridemia and this observation was also statistically significant (OR=10.78, 95%CI= 1.35-86.15, P=0.007). In patients of NAFLD with diabetes mellitus 10(71.4%) had increased levels of LDL while in patients of NAFLD patients without diabetes mellitus 21(24.4%) had increased levels of LDL and this observation was statistically significant (OR=7.738, 95%CI=22.13-41.03, P=0.001). In patients of NAFLD with diabetes mellitus 14(100%) had increased BMI while in patients of NAFLD patients without diabetes mellitus 63(73.3%) had increased BMI. Although difference is quite large but this observation was not statistically significant (p=0.07). 

In our study, positive correlation of T2DM with hypertension, hypertriglyceridemia and elevated levels of LDL was found, and these observations were statistically significant. All T2DM patients had increased BMI, Low HDL was found in 92.9% of diabetic patients, although these observations were not statistically significant. These findings are suggestive of strong association between NAFLD, T2DM and Metabolic syndrome.

The prevalence of abnormal glucose metabolism in NAFLD patients is much higher than in previously reported studies. Patients with NAFLD may benefit from early screening for Diabetes Mellitus to prevent the long-term complications of hyperglycemia and progression to steatohepatitis and cirrhosis. 

Our study also reveals that there is higher prevalence of various components of metabolic syndrome in the patients of NAFLD. Patients must be evaluated for presence of NAFLD by abdominal ultrasonography, whenever these parameters are encountered in the clinical setting. Its early detection may help in modifying the disease course and delaying complications.

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