Prevalence of prediabetes and diabetes and metabolic profile of patients with nonalcoholic fatty liver disease (NAFLD).

OBJECTIVE: Prediabetes and type 2 diabetes mellitus (T2DM) are believed to be common and associated with a worse metabolic profile in patients with nonalcoholic fatty liver disease (NAFLD). However, no previous study has systematically screened this population. RESEARCH DESIGN AND METHODS: We studied the prevalence and the metabolic impact of prediabetes and T2DM in 118 patients with NAFLD. The control group comprised 20 subjects without NAFLD matched for age, sex, and adiposity. We measured 1) plasma glucose, insulin, and free fatty acid (FFA) concentration during an oral glucose tolerance test; 2) liver fat by magnetic resonance spectroscopy (MRS); 3) liver and muscle insulin sensitivity (euglycemic insulin clamp with 3-[(3)H]glucose); and 4) indexes of insulin resistance (IR) at the level of the liver (HIR(i)= endogenous glucose production × fasting plasma insulin [FPI]) and adipose tissue (Adipo-IR(i)= fasting FFA × FPI). RESULTS: Prediabetes and T2DM was present in 85% versus 30% in controls (P < 0.0001), all unaware of having abnormal glucose metabolism. NAFLD patients were IR at the level of the adipose tissue, liver, and muscle (all P < 0.01-0.001). Muscle and liver insulin sensitivity were impaired in patients with NAFLD to a similar degree, whether they had prediabetes or T2DM. Only adipose tissue IR worsened in T2DM and correlated with the severity of muscle (r = 0.34; P < 0.001) and hepatic (r = 0.57; P < 0.0001) IR and steatosis by MRS (r = 0.35; P < 0.0001). CONCLUSIONS: Patients with NAFLD may benefit from early screening for T2DM, because the prevalence of abnormal glucose metabolism is much higher than previously appreciated. Regardless of glucose tolerance status, severe IR is common. In patients with T2DM, adipose tissue IR appears to play a major role in the severity of NAFLD.

Effect of adipose tissue insulin resistance on metabolic parameters and liver histology in obese patients with nonalcoholic fatty liver disease.

UNLABELLED: The role of adipose tissue insulin resistance in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) remains unclear. To evaluate this, we measured in 207 patients with NAFLD (age = 51 ± 1, body mass index = 34.1 ± 0.3 kg/m(2) ) and 22 controls without NAFLD (no NAFLD) adipose tissue insulin resistance by means of a validated index (Adipo-IR(i) = plasma free fatty acids [FFA] x insulin [FPI] concentration) and as the suppression of plasma FFA during an oral glucose tolerance test and by a low-dose insulin infusion. We also explored the relationship between adipose tissue insulin resistance with metabolic and histological parameters by dividing them based on quartiles of adipose tissue insulin resistance (Adipo-IR(i) quartiles: Q1 = more sensitive; Q4 = more insulin resistant). Hepatic insulin resistance, measured as an index derived from endogenous glucose production x FPI (HIRi), and muscle insulin sensitivity, were assessed during a euglycemic insulin clamp with 3-[(3) H] glucose. Liver fat was measured by magnetic resonance imaging and spectroscopy, and a liver biopsy was performed to assess liver histology. Compared to patients without steatosis, patients with NAFLD were insulin resistant at the level of adipose tissue, liver, and skeletal muscle and had higher plasma aspartate aminotransferase and alanine aminotransferase, triglycerides, and lower high-density lipoprotein cholesterol and adiponectin levels (all P < 0.01). Metabolic parameters, hepatic insulin resistance, and liver fibrosis (but not necroinflammation) deteriorated as quartiles of adipose tissue insulin resistance worsened (all P < 0.01). CONCLUSION: Adipose tissue insulin resistance plays a key role in the development of metabolic and histological abnormalities of obese patients with NAFLD. Treatment strategies targeting adipose tissue insulin resistance (e.g., weight loss and thiazolidinediones) may be of value in this population.

Role of ethnicity in overweight and obese patients with nonalcoholic steatohepatitis.

UNLABELLED: The role of ethnicity in determining disease severity in nonalcoholic steatohepatitis (NASH) remains unclear. We recruited 152 patients with biopsy-proven NASH, 63% of whom were Hispanic and 37% of whom were Caucasian. Both groups were well matched for age, sex, and total body fat. We measured: (1) liver fat by magnetic resonance imaging and spectroscopy; (2) fasting plasma glucose, fasting plasma insulin (FPI), and free fatty acid (FFA) levels; (3) total body fat by dual energy x-ray absorptiometry (DXA); (4) liver and muscle insulin sensitivity (insulin clamp with 3-[(3)H] glucose); (5) insulin resistance at the level of the liver (fasting endogenous glucose production derived from 3-[(3)H] glucose infusion × FPI) and adipose tissue (fasting FFA × FPI). Liver fat was slightly, but not significantly, higher in Hispanic vs. Caucasian patients (27 ± 2% vs. 24 ± 2%, p = 0.16). However, this trend did not translate into worse liver steatosis, necroinflammation or fibrosis. Patients with NASH had severe hepatic, adipose tissue and muscle insulin resistance versus healthy subjects without NASH nonalcoholic fatty liver disease, but there were no differences between both ethnic groups on these parameters. However, Hispanics versus Caucasians with type 2 diabetes mellitus (T2DM) had a trend for worse hepatic/adipose tissue insulin resistance and fibrosis. CONCLUSION: When Hispanic and Caucasian patients with NASH are well matched for clinical parameters, particularly for adiposity, slightly higher liver fat content is not associated with worse hepatic insulin resistance or more severe NASH on histology. Hispanic ethnicity does not appear to be a major determinant of disease severity in NASH, although those with diabetes may be at greater risk of fibrosis. Given the higher risk of T2DM in Hispanics, long-term studies are needed to define their risk of disease progression.

Pioglitazone treatment increases whole body fat but not total body water in patients with non-alcoholic steatohepatitis.

BACKGROUND/AIMS: Non-Alcoholic Steatohepatitis (NASH) is a chronic liver disease frequently associated with insulin resistance and type 2 diabetes mellitus (T2DM). Pioglitazone reverses the metabolic and histological abnormalities of patients with impaired glucose tolerance or T2DM and NASH, but also leads to weight gain. To understand the nature of weight gain associated with pioglitazone treatment in NASH we analyzed 35 patients who completed tests for determination of whole body fat (WBF) and total body water (TBW). METHODS: Twenty-one patients received pioglitazone and 14 placebo in a double-blind, randomized fashion for a period of 6 months. WBF and TBW were measured before and after treatment using DXA, a water dilution technique and bioimpedance. RESULTS: Pioglitazone increased body weight (from 93.6+/-4.2 to 96.1+/-4.5 kg, p<0.003) and WBF measured with DXA (from 32.9+/-2.1 to 35.4+/-2.5 kg, p<0.002) while no changes were seen with placebo. Total body water was not altered significantly either after pioglitazone (from 45.4+/-2.3 to 45.6+/-2.7 l, p=NS) or placebo. Muscle hydration and extracellular water were unchanged both by pioglitazone and placebo treatments. CONCLUSIONS: Six months of pioglitazone treatment in patients with NASH is associated with weight gain that is attributable to an increase in adipose tissue mass and not to water retention.

A placebo-controlled trial of pioglitazone in subjects with nonalcoholic steatohepatitis.

BACKGROUND: No pharmacologic therapy has conclusively proved to be effective for the treatment of nonalcoholic steatohepatitis, which is characterized by insulin resistance, steatosis, and necroinflammation with or without centrilobular fibrosis. Pioglitazone is a thiazolidinedione that ameliorates insulin resistance and improves glucose and lipid metabolism in type 2 diabetes mellitus. METHODS: We randomly assigned 55 patients with impaired glucose tolerance or type 2 diabetes and liver biopsy-confirmed nonalcoholic steatohepatitis to 6 months of treatment with a hypocaloric diet (a reduction of 500 kcal per day in relation to the calculated daily intake required to maintain body weight) plus pioglitazone (45 mg daily) or a hypocaloric diet plus placebo. Before and after treatment, we assessed hepatic histologic features, hepatic fat content by means of magnetic resonance spectroscopy, and glucose turnover during an oral glucose tolerance test ([14C]glucose given with the oral glucose load and [3H]glucose given by intravenous infusion). RESULTS: Diet plus pioglitazone, as compared with diet plus placebo, improved glycemic control and glucose tolerance (P<0.001), normalized liver aminotransferase levels as it decreased plasma aspartate aminotransferase levels (by 40% vs. 21%, P=0.04), decreased alanine aminotransferase levels (by 58% vs. 34%, P<0.001), decreased hepatic fat content (by 54% vs. 0%, P<0.001), and increased hepatic insulin sensitivity (by 48% vs. 14%, P=0.008). Administration of pioglitazone, as compared with placebo, was associated with improvement in histologic findings with regard to steatosis (P=0.003), ballooning necrosis (P=0.02), and inflammation (P=0.008). Subjects in the pioglitazone group had a greater reduction in necroinflammation (85% vs. 38%, P=0.001), but the reduction in fibrosis did not differ significantly from that in the placebo group (P=0.08). Fatigue and mild lower-extremity edema developed in one subject who received pioglitazone; no other adverse events were observed. CONCLUSIONS: In this proof-of-concept study, the administration of pioglitazone led to metabolic and histologic improvement in subjects with nonalcoholic steatohepatitis. Larger controlled trials of longer duration are warranted to assess the long-term clinical benefit of pioglitazone. (ClinicalTrials.gov number, NCT00227110 [ClinicalTrials.gov] .).