Effects of neuromuscular electrical stimulation on glycemic control: a systematic review and meta-analysis.

Background: Physical inactivity increases the risk for metabolic diseases such as obesity and type 2 diabetes. Neuromuscular electrical stimulation (NMES) is an effective method to induce muscle contraction, particularly for populations with physical impairments and/or metabolic diseases. However, its effectiveness to improve glycemic control is unclear. This review aimed to determine the effectiveness of NMES on glycemic control. Methods: Electronic search consisted of MEDLINE (PubMed), EMBASE, Cochrane Library, Google Scholar, and Web of Science to identify studies that investigated the effects of NMES on glycemic control for this systematic review. The meta-analysis consists of the studies designed as randomized controlled trials. Effect sizes were calculated as the standardized mean difference (SMD) and meta-analysis was conducted using a random-effects model. Results: Thirty-five studies met the inclusion criteria for systematic review and of those, nine qualified for the meta-analysis. Existing evidence suggested that NMES effectively improves glycemic control predominantly in middle-aged and elderly population with type 2 diabetes, obesity, and spinal cord injury. The meta-analysis is comprised of 180 participants and reported that NMES intervention lowered fasting blood glucose (SMD: 0.48; 95% CI: 0.17 to 0.78; p=0.002; I²=0%). Additional analysis using the primary measures reported by each study to indicate glycemic control (i.e., OGTT, HOMA-IR, and fasting glucose) also confirmed a significant effect of NMES on improving glycemic control (SMD: 0.41; 95% CI, 0.09 to 0.72; p=0.01; I²=11%). NMES protocol varied across studies and requires standardization. Conclusion: NMES could be considered as a therapeutic strategy to improve glycemic control in populations with physical impairments and/or metabolic disorders. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42020192491.

Four weeks of electrical stimulation improves glucose tolerance in a sedentary overweight or obese Hispanic population.

Introduction/purpose: Most US adults (54%) do not meet the minimum exercise recommendations by the American College of Sports Medicine. Neuromuscular electrical stimulation (NMES) is a novel alternate strategy to induce muscle contraction. However, the effectiveness of NMES to improve insulin sensitivity and energy expenditure is unclear. The purpose of this study was to investigate the effects of 4 weeks of NMES on glucose tolerance in a sedentary overweight or obese population. Methods: Participants (n = 10; age: 36.8 ± 3.8 years; BMI = 32 ± 1.3 kg/m2) were randomized into either control or NMES group. All participants received bilateral quadriceps stimulation (12 sessions; 30 min/session; three times/week at 50 Hz and 300 µs pulse width) altering pulse amplitude to either provide low-intensity sensory level (control; tingling sensation) or at high-intensity neuromuscular level (NMES; maximum tolerable levels with visible muscle contraction). Glucose tolerance was assessed by a 3-h oral glucose tolerance test (OGTT), and substrate utilization was measured by indirect calorimetry and body composition via dual X-ray absorptiometry at baseline and after 4 weeks of NMES intervention. Results: Control and NMES groups had comparable fasting blood glucose, glucose tolerance, substrate utilization, and muscle mass at baseline. Four weeks of NMES resulted in a significant improvement in glucose tolerance measured by OGTT, whereas no change was observed in the control group. There was no change in substrate utilization and muscle mass in both control and NMES groups. Conclusion: NMES is a novel and effective strategy to improve glucose tolerance in an at-risk overweight or obese sedentary population.