Skeletal muscle and organ masses differ in overweight adults with type 2 diabetes

Abstract

Whether lean body mass (LBM) composition, especially skeletal muscle and abdominal organs, differs in adults with type 2 diabetes (T2DM) compared with nondiabetic healthy controls has not been investigated. A subset of African-American and Caucasian participants with T2DM from the Look AHEAD (Action for Health in Diabetes) trial had body composition assessed and compared with a sample of healthy controls. Skeletal muscle mass (SMM), liver, kidneys, and spleen mass were quantified using a contiguous slice magnetic resonance imaging (MRI) protocol. Cardiac mass was quantified by either a cardiac gated MRI protocol or by echocardiography. MRI volumes were converted to mass using assumed densities. Dual-energy X-ray absorptiometry assessed LBM. Using general linear models adjusted for height, weight, sex, age, race, and interactions of diabetes status with race or sex, persons with T2DM (n ϭ 95) had less LBM (49.7 vs. 51.6 kg) and SMM (24.1 vs. 25.4 kg) and larger kidneys (0.40 vs. 0.36 kg) than controls (n ϭ 76) (all P Ͻ 0.01). Caucasians with T2DM had larger livers (1.90 vs. 1.60 kg, P Ͻ 0.0001) and spleens (0.29 vs. 0.22 kg, P Ͻ 0.01), and T2DM men had less cardiac mass than controls (0.25 vs. 0.30 kg, P Ͻ 0.001). In this sample, T2DM is characterized by less relative skeletal muscle and cardiac mass in conjunction with larger kidneys, liver, and spleen. Further investigation is needed to establish the causes and metabolic consequences of these race-and sex-specific organ mass differences in T2DM. African American; Caucasian; magnetic resonance imaging; kidneys; liver; spleen THE CHARACTERIZATION OF BODY composition in persons with type 2 diabetes mellitus (T2DM) has been largely limited to fat distribution and its effects on metabolic disease (2,3,23,24,40,(43)(44)(45). Because skeletal muscle mass is the major site of glucose disposal and insulin uptake (52), it is of clinical importance to know whether this metabolically important tissue, which constitutes ϳ75% of total body lean mass in healthy adults (46), is preserved in persons with T2DM. Longitudinal data in older adults indicate that the age-associated reduction in thigh cross-sectional area and appendicular lean mass is accelerated in women with T2DM compared with healthy controls, but this difference was not found in men (35). Another possible contributor to the apparent differences in the quantity of lean tissue mass lost in individuals with T2DM may be the effect of race. Recent evidence links the established energy expenditure differences between African Americans and Caucasians (18, 29) to discrepancies in high-metabolic-rate organ masses such as liver, kidneys, heart, spleen, and brain (15). Whether these sex-and race-dependent effects on skeletal muscle or organ mass affect lean tissue preservation in persons with diabetes, a disease state that directly affects protein metabolism (19,37) and may influence the relative size of lean tissues and organs, is still unknown.The primary aim of this study was to assess lean body mass (LBM), skeletal muscl...

Changes in skeletal muscle and organ size after a weight-loss intervention in overweight and obese type 2 diabetic patients

“…Least-squares means are from maximum-likelihood linear regression models with between-subject groups (DSE and ILI), time as a repeated measure, and time-by-group interactions. DSE, diabetes support and education; ILI, intensive lifestyle intervention; T0, baseline; T12, 1 y; T24, 2 y. organs including liver in both patients with type 2 diabetes mellitus and healthy control subjects have been previously reported by our group (14). Although in African Americans liver size was 13% larger in patients with type 2 diabetes mellitus than in healthy control subjects, in Caucasians livers were 40% larger.…”

“…Information on duration of diabetes (length of time since diagnosis) and whether the patient was taking medication or insulin was obtained from the parent trial. Selected results from the Look AHEAD trial (9-13) and some findings of this MRI ancillary study have been published (8,14,15). All studies were approved by the Institutional Review Board of St. Luke's-Roosevelt Hospital or the University of Pittsburgh, and each subject gave written consent before data were collected.…”

Skeletal muscle dysfunction in the db/db mouse model of type 2 diabetes

“…16,20 Apart from this, T2DM is, in general, associated with neuropathy 2,4,5 and muscle atrophy. 9 Accordingly, the muscles from the db/db mice in this study weighed 10% less than muscles from control mice, even though the db/db mice were clearly obese, with body weights around 1.75-fold higher than controls. The mechanism causing muscle atrophy in diabetes is unclear but could involve disuse and, for some muscle fibers, complete loss of functional innervation.…”

“…In T2DM, increased weakness has been associated with reduced force generation capacity caused by muscle atrophy and failure of neuromuscular transmission . Theoretically, transmission failure may take place at any point in the neuromuscular system and could include axonal damage of motor nerves causing compromised action potential propagation, reduced safety factor of neuromuscular transmission, or decreased excitability of muscle fibers.…”

Fat-free mass is not lower 24 months postbariatric surgery than nonoperated matched controls

“…Preservation of FFM or, more specifically, skeletal muscle mass, is important to future health since skeletal mass is associated with muscular strength and endurance, improved insulin sensitivity, increased high-density lipoprotein cholesterol, and enhanced psychological well-being [3]. FFM loss or, more specifically, its constituents’ skeletal muscle mass and high metabolic rate organ mass have been a focus of continual concern for its possible effect on basal metabolic rate, core body temperature, rate of weight loss, weight regain, and or the possible development of protein deficiency [4,5]. Therefore assessments of body composition change during the weight loss process, which record substantial changes in FFM, have resulted in strong efforts to increase protein intake and physical exercise in an attempt to limit FFM losses.…”