Association of diffuse liver glycogenosis and mild focal macrovesicular steatosis in a patient with poorly controlled type 1 diabetes

Hepatopathy Associated With Type 1 Diabetes: Distinguishing Non-alcoholic Fatty Liver Disease From Glycogenic Hepatopathy

Autoimmune destruction of pancreatic β-cells results in the permanent loss of insulin production in type 1 diabetes (T1D). The daily necessity to inject exogenous insulin to treat hyperglycemia leads to a relative portal vein insulin deficiency and potentiates hypoglycemia which can induce weight gain, while daily fluctuations of blood sugar levels affect the hepatic glycogen storage and overall metabolic control. These, among others, fundamental characteristics of T1D are associated with the development of two distinct, but in part clinically similar hepatopathies, namely non-alcoholic fatty liver disease (NAFLD) and glycogen hepatopathy (GlyH). Recent studies suggest that NAFLD may be increasingly common in T1D because more people with T1D present with overweight and/or obesity, linked to the metabolic syndrome. GlyH is a rare but underdiagnosed complication hallmarked by extremely brittle metabolic control in, often young, individuals with T1D. Both hepatopathies share clinical similarities, troubling both diagnosis and differentiation. Since NAFLD is increasingly associated with cardiovascular and chronic kidney disease, whereas GlyH is considered self-limiting, awareness and differentiation between both condition is important in clinical care. The exact pathogenesis of both hepatopathies remains obscure, hence licensed pharmaceutical therapy is lacking and general awareness amongst physicians is low. This article aims to review the factors potentially contributing to fatty liver disease or glycogen storage disruption in T1D. It ends with a proposal for clinicians to approach patients with T1D and potential hepatopathy.

Glycogenic hepatopathy

BACKGROUND

Glycogenic hepatopathy (GH) is a disorder associated with uncontrolled diabetes mellitus, most commonly type 1, expressed as right upper quadrant abdominal pain, hepatomegaly and increased liver enzymes. The diagnosis may be difficult, because laboratory and imaging tests are not pathognomonic. Although GH may be suggested based on clinical presentation and imaging studies, the gold standard for diagnosis is a liver biopsy, showing a significant accumulation of glycogen within the hepatocytes. GH may be diagnosed also after elevated liver enzymes in routine blood tests. GH usually regresses after tight glycemic control. Progression to end-stage liver disease has never been reported. This review aims to increase the awareness to this disease, to suggest a pathway for investigation that may reduce the use of unnecessary tests, especially invasive ones.

DATA SOURCES

A PubMed database search (up to July 1, 2017) was done with the words "glycogenic hepatopathy", "hepatic glycogenosis", "liver glycogenosis" and "diabetes mellitus-associated glycogen storage hepatopathy". Articles in which diabetes mellitus-associated liver glycogen accumulation was described were included in this review.

RESULTS

A total of 47 articles were found, describing 126 patients with GH. Hepatocellular disturbance was more profound than cholestatic disturbance. No synthetic failure was reported.

CONCLUSIONS

GH may be diagnosed conservatively, based on corroborating medical history, physical examination, laboratory tests, imaging studies and response to treatment, even without liver biopsy. In case of doubt about the diagnosis or lack of clinical response to treatment, a liver biopsy may be considered. There is no role for noninvasive tests like fibroscan or fibrotest for the diagnosis of GH or for differentiation of this situation from nonalcoholic fatty liver disease.

Focal Hepatic Glycogenosis in a Patient With Uncontrolled Diabetes Mellitus Type 1

Hepatomegaly and elevated liver enzymes in patients with diabetes are commonly associated with fatty liver disease. However, physicians often forget about another intrinsic substance that can cause a similar clinical picture-glycogen. Liver stores approximately one third of the total body glycogen and is responsible for blood glucose homeostasis. Excessive hepatocellular glycogen accumulation occurs not only in congenital glycogen storage diseases, but also in acquired conditions associated with hyperglycemic-hyperinsulinemic states such as uncontrolled diabetes mellitus, high-dose corticosteroid use, and dumping syndrome. All reported cases of acquired abnormal glycogen deposition described a diffuse form of hepatic glycogenosis with the entire liver involved in the accumulating process. To our knowledge, this is the first reported case of abnormal focal glycogen deposition in a patient with diabetes mellitus type 1 with imaging and pathologic correlation. Awareness of the imaging appearance of focal glycogen deposition can help to distinguish it from other pathologic conditions.

Diagnosis of hepatic glycogenosis in poorly controlled type 1 diabetes mellitus

Hepatic glycogenosis (HG) in type 1 diabetes is a underrecognized complication. Mauriac firstly described the syndrome characterized by hepatomegaly with altered liver enzymes, growth impairment, delay puberty and Cushingoid features, during childhood. HG in adulthood is characterized by the liver disorder (with circulating aminotransferase increase) in the presence of poor glycemic control (elevation of glycated hemoglobin, HbA1c levels). The advances in the comprehension of the metabolic pathways driving to the hepatic glycogen deposition point out the role of glucose transporters and insulin mediated activations of glucokinase and glycogen synthase, with inhibition of glucose-6-phosphatase. The differential diagnosis of HG consists in the exclusion of causes of liver damage (infectious, metabolic, obstructive and autoimmune disease). The imaging study (ultrasonography and/or radiological examinations) gives information about the liver alterations (hepatomegaly), but the diagnosis needs to be confirmed by the liver biopsy. The main treatment of HG is the amelioration of glycemic control that is usually accompanied by the reversal of the liver disorder. In selected cases, more aggressive treatment options (transplantation) have been successfully reported.

Metabolic factors in the development of hepatic steatosis and altered mitochondrial gene expression in vivo

The objective of the study was to understand the role in vivo of elevated plasma free fatty acids (FFA), insulin, and glucose levels in the development of steatosis and altered mitochondrial gene/protein expression. We studied 4 groups of Sprague-Dawley rats: (1) high-fat diet (HFD), (2) high-dose streptozotocin-induced diabetes (T1DM), (3) low-dose streptozotocin-induced diabetic rats on an HFD (T2DM), and (4) controls. Liver histology and expression of genes/proteins related to mitochondrial fatty acid oxidation and biogenesis were analyzed. Despite an attempt to compensate by increasing expression of genes of fatty acid oxidation (carnitine palmitoyl transferase-1/medium chain acyl-CoA dehydrogenase), the HFD and diabetic groups developed marked steatosis and suffered a significant reduction in mitochondrial biogenesis gene expression (nuclear respiratory factor 1/transcriptional factor A, mitochondrial). In T2DM rats, the combination of high glucose and FFA unexpectedly did not lead to greater fat accumulation than HFD alone. Greater steatosis in HFD vs T2DM (P < .001) correlated with impairment in the gene expression of PPAR-α (ie, fatty acid oxidation) and PGC1α, a major coactivator for mitochondrial biogenesis. Steatosis was not severe in insulin-deficient T1DM rats despite very elevated FFA and glucose levels. Increased carnitine palmitoyl transferase-1/medium chain acyl-CoA dehydrogenase/PPAR-α gene expression suggested inadequate adaptation to high FFA in both T1DM/T2DM rats. Hyperinsulinemia combined with elevated FFA is the key metabolic factor driving hepatic lipogenesis in vivo (HFD rats). Mitochondrial biogenesis (nuclear respiratory factor 1; transcriptional factor A, mitochondrial) is highly susceptible to FFA-induced steatosis. In contrast, hyperglycemia does not have an additive effect (T2DM) and leads to only a modest degree of steatosis in the absence of hyperinsulinemia, even when FFA are extremely elevated as in T1DM rats.

Morphology and protein content of hepatocytes in type I diabetic rats submitted to physical exercises

The importance of physical exercise practice in the treatment of diabetes has been reported in many studies recently, but only limited data can be found regarding its benefits on liver morphology and protein content of hepatocytes. In order to assess the changes arising from the development of type I diabetes and the benefits of a training protocol, Wistar rats were divided into four groups: sedentary control (SC), trained control (TC), sedentary diabetic (SD) and trained diabetic (TD). The training protocol consisted of swimming for 60 min a day, 5 days/week, during 8 weeks. Liver samples were collected, processed and analyzed by histochemical and ultrastructural techniques. Biochemical tests were also conducted to examine the protein content and quantity of DNA in the liver. In morphological assessment, the presence of areas of cytoplasmic basophilia observed in control subjects was not visualized in sedentary diabetics. It was related to differences in the amount of mitochondria in the cytosol. The mitochondrial structure has not undergone relevant changes, and the number of rough endoplasmic reticulum cisterns was clearly inferior in sedentary diabetics, suggesting lower protein production. However, the biochemical analysis of protein content indicated no statistical differences between groups. The exercise, in turn, was not responsible for major changes in these characteristics. On the whole, the morphological damages arising from type I diabetes were noteworthy. Nevertheless, regular physical training was not responsible for significant improvements in some respects, making evident the need for combined application of a distinct form of treatment.