Response to Comments on Nolan et al. Insulin Resistance as a Physiological Defense Against Metabolic Stress: Implications for the Management of Subsets of Type 2 Diabetes. Diabetes 2015;64:673-686

Nonalcoholic fatty liver disease and type 2 diabetes: pathophysiological mechanisms shared between the two faces of the same coin

The pathophysiological mechanisms underlying the close relationship between nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) are multiple, complex and only partially known. The purpose of this paper was to review the current knowledge of these mechanisms in a unified manner. Subjects with NAFLD and T2DM have established insulin resistance (IR), which exacerbates the two comorbidities. IR worsens NAFLD by increasing the accumulation of free fatty acids (FFAs) in the liver. This occurs due to an increase in the influx of FFAs from peripheral adipose tissue by the activation of hormone-sensitive lipase. In addition, there is de novo increased lipogenesis, a transcription factor, the sterols regulatory element-binding transcription factor 1c (SREBP-1c), which activates the expression of several genes strongly promotes lipogenesis by the liver and facilitate storage of triglycerides. Lipids accumulation in the liver induces a chronic stress in the endoplasmic reticulum of the hepatocytes. Genome-wide association studies have identified genetic variants associated with NAFLD severity, but unrelated to IR. In particular, the alteration of patatin-like phospholipase domain-containing protein 3 contributes to the susceptibility to NAFLD. Furthermore, the lipotoxicity of ceramides and diacylglycerol, well known in T2DM, triggers a chronic inflammatory process favoring the progression from hepatic steatosis to steatohepatitis. Reactive oxygen species produced by mitochondrial dysfunction trigger both liver inflammation and beta-cells damage, promoting the progression of both NAFLD and T2DM. The close association between NAFLD and T2DM is bidirectional, as T2DM may trigger both NAFLD onset and its progression, but NAFLD itself may contribute to the development of IR and T2DM. Future studies on the mechanisms will have to deepen the knowledge of the interaction between the two pathologies and should allow the identification of new therapeutic targets for the treatment of NAFLD, currently substantially absent.

Transitioning to non-insulin therapy in a patient receiving high dose insulin

In people with type 2 diabetes with evidence of obesity-related insulin resistance, use of insulin to treat hyperglycemia has not been shown to reduce macrovascular complications, despite widespread use for many years. However, newer classes of diabetes medications, designed to address the prevalent pathophysiologic defect of type 2 diabetes, have emerged. Consequently, in many patients, reduction of insulin doses or even total elimination is possible after the addition of these newer agents. The authors suggest a cautious approach in which people with type 2 diabetes and established cardiovascular disease who are on high insulin doses (>1.0 unit/kg/day) be treated with diabetes medications that showed evidence of cardiovascular benefit (such as glucagon-like peptide-1 receptor agonists [GLP-1RAs]), on whom close monitoring is crucial because they may be at particular risk for developing hypoglycemia. This approach can be labor intensive and may be challenging for busy primary care providers for who may have limited time to evaluate and follow the patient. The authors present a case report of adding a GLP-1RA to high insulin doses. If the hemoglobin A1c is <8.0% when GLP-1RA is added, insulin doses should be reduced by 20%. Patients should be monitored at least every 4 weeks initially until it is confirmed there is no hypoglycemia risk. If glycemic targets (defined as fasting or preprandial glucose level between 80 and 130 mg/dl) are consistently achieved, providers may consider proactively reducing insulin doses by 10-20% to avoid hypoglycemia. The authors recommend creating appropriate goals and expectation before initiating this process.

The Use of Technology for Estimating Body CompositionStrengths and Weaknesses of Common Modalities in a Clinical Setting [Formula: see text]

Assessment of body composition, both at single time points and longitudinally, is particularly important in clinical nutrition practice. It provides a means for the clinician to characterize nutrition status at a single time point, aiding in the identification and diagnosis of malnutrition, and to monitor changes over time by providing real-time information on the adequacy of nutrition interventions. Objective body composition measurement tools are available clinically but are often underused in nutrition care, particularly in the United States. This is, in part, due to a number of factors concerning their use in a clinical context: cost and accessibility of equipment, as well as interpretability of the results. This article focuses on the factors influencing interpretation of results in a clinical setting. Body composition assessment, regardless of the method, is inherently limited by its indirect nature. Therefore, an understanding of the strengths and limitations of any method is essential for meaningful interpretation of its results. This review provides an overview of body composition technologies available clinically (computed tomography, dual-energy x-ray absorptiometry, bioimpedance, ultrasound) and discusses the strengths and limitations of each device.