Non-alcoholic fatty liver disease (NAFLD) is categorized by non-alcoholic hepatic steatosis. Although hepatic steatosis and steatohepatitis are majorly linked with multiple diseases affecting the liver, such as hepatitis A, B and C, autoimmune hepatitis, hemochromatosis, and hypothyroidism. It has been witnessed to be extremely predominant in patients with type 2 diabetes mellitus (T2D). Epidemiological surveys suggest that the prevalence of NAFLD in obese adults with T2DM are greater than 70%. This high prevalence is suggestive of the presence of obesity and insulin resistance in T2DM. Evidences documented that alanine aminotransferase, which is responsible for most cases in NAFLD is reported to be more than twice normal in 20% of children with T2DM. 

Though the pathogenesis of NAFLD is still not completely understood, insulin resistance is a crucial contributing factor. In addition, obesity is considered as the most frequent cause of the insulin resistant state. This production of free fatty acids causes increase in generation of excess triglyceride in the liver which is aggravated by impaired hepatic fatty acid oxidation secondary to insulin resistance. Glucose content in pre-diabetes or overt diabetics also augments the substrate for triglyceride synthesis. Furthermore, impaired very low density lipoprotein (VLDL) secretion, results from insulin resistance, increases fat deposition in the liver. Thus, insulin resistance is seen commonly with NAFLD in regard to obesity, and NAFLD also progresses in relation with both insulin resistance and a state of excess calorie intake.

It has been observed that there is an elevated risk of NAFLD secondary to diabetes, as well as NAFLD ca be considered a risk factor for developing T2DM. Moreover, researches also demonstrated that diabetes can be regarded as independent risk factor causing progression of NAFLD to stages like cirrhosis. Therefore, it is essential to evaluate the effects of diabetes on NAFLD progression to nonalcoholic steatohepatitis (NASH), along with its incidence with diabetes while analysing the association between DM and NAFLD.

Source: Bhatt HB, Smith RJ. Fatty liver disease in diabetes mellitus. Hepatobiliary Surg Nutr. 2015;4(2):101-108.