Selective antagonism of somatostatin receptor type 2 (SSTR2) normalizes glucagon and corticosterone responses to hypoglycemic clamp in diabetic rats. The purpose of this study was to determine whether SSTR2 antagonism (SSTR2a) ameliorates hypoglycemia in response to overinsulinization in diabetic rats previously exposed to recurrent hypoglycemia. Streptozotocin diabetic rats (n = 19), previously subjected to five hypoglycemia events over 3 days, received an insulin bolus (10 units/kg i.v.) plus insulin infusion (50 mU/kg/min i.v.) until hypoglycemia ensued (≤3.9 mmol/L) (experimental day 1 [Expt-D1]). The next day (Expt-D2), rats were allocated to receive either placebo treatment (n = 7) or SSTR2a infusion (3,000 nmol/kg/min i.v., n = 12) 60 min prior to the same insulin regimen. On Expt-D1, all rats developed hypoglycemia by ∼90 min, while on Expt-D2, hypoglycemia was attenuated with SSTR2a treatment (nadir = 3.7 ± 0.3 vs. 2.7 ± 0.3 mmol/L in SSTR2a and controls, P < 0.01). Glucagon response to hypoglycemia on Expt-D2 deteriorated by 20-fold in the placebo group (P < 0.001) but improved in the SSTR2a group (threefold increase in area under the curve [AUC], P < 0.001). Corticosterone response deteriorated in the placebo-treated rats on Expt-D2 but increased twofold in the SSTR2a group. Catecholamine responses were not affected by SSTR2a. Thus, SSTR2 antagonism after recurrent hypoglycemia improves the glucagon and corticosterone responses and largely ameliorates insulin-induced hypoglycemia in diabetic rats.
OBJECTIVE Patients with type 1 diabetes who do aerobic exercise often experience a drop in blood glucose concentration that can result in hypoglycemia. Current approaches to prevent exercise-induced hypoglycemia include reduction in insulin dose or ingestion of carbohydrates, but these strategies may still result in hypoglycemia or hyperglycemia. We sought to determine whether mini-dose glucagon (MDG) given subcutaneously before exercise could prevent subsequent glucose lowering and to compare the glycemic response to current approaches for mitigating exercise-associated hypoglycemia. RESEARCH DESIGN AND METHODS We conducted a four-session, randomized crossover trial involving 15 adults with type 1 diabetes treated with continuous subcutaneous insulin infusion who exercised fasting in the morning at ∼55% VO2max for 45 min under conditions of no intervention (control), 50% basal insulin reduction, 40-g oral glucose tablets, or 150-μg subcutaneous glucagon (MDG). RESULTS During exercise and early recovery from exercise, plasma glucose increased slightly with MDG compared with a decrease with control and insulin reduction and a greater increase with glucose tablets (P < 0.001). Insulin levels were not different among sessions, whereas glucagon increased with MDG administration (P < 0.001). Hypoglycemia (plasma glucose <70 mg/dL) was experienced by six subjects during control, five subjects during insulin reduction, and none with glucose tablets or MDG; five subjects experienced hyperglycemia (plasma glucose ≥250 mg/dL) with glucose tablets and one with MDG. CONCLUSIONS MDG may be more effective than insulin reduction for preventing exercise-induced hypoglycemia and may result in less postintervention hyperglycemia than ingestion of carbohydrate.
One hundred years ago, insulin was first used to successfully lower blood glucose levels in young people living with what was then called juvenile diabetes. While insulin was not a cure for diabetes, it allowed individuals to resume a near normal life and have some freedom to eat more liberally and gain the strength they needed to live a more active lifestyle. Since then, a number of therapeutic and technical advances have arisen to further improve the health and wellbeing of individuals living with type 1 diabetes, allowing many to participate in sport at the local, regional, national or international level of competition. This review and commentary highlights some of the key advances in diabetes management in sport over the last 100 years since the discovery of insulin.
The angiostatic nature of pharmacological doses of glucocorticoid steroids is well known. However, the consequences of pathophysiological elevation of endogenous glucocorticoids are not well established. In the current study, we hypothesized that the angiostatic effect of corticosterone, an endogenous glucocorticoid in rodents, occurs through multi-faceted alterations in skeletal muscle microvascular endothelial cell proliferation, migration, and proteolysis. Chronic corticosterone treatment significantly reduced the capillary to fiber ratio in the tibialis anterior muscle compared to that of placebo-treated rats. Corticosterone inhibited endothelial cell sprouting from capillary segments ex vivo. Similarly, 3-dimensional endothelial cell spheroids treated with corticosterone for 48 hours showed evidence of sprout regression and reduced sprout length. Endothelial cell proliferation was reduced in corticosterone treated cells, coinciding with elevated FoxO1 and reduced VEGF production. Corticosterone treated endothelial cells exhibited reduced migration, which correlated with a reduction in RhoA activity. Furthermore, corticosterone treated endothelial cells in both 3-dimensional and monolayer cultures had decreased MMP-2 production and activation resulting in decreased proteolysis by endothelial cells, limiting their angiogenic potential. Promoter assays revealed that corticosterone treatment transcriptionally repressed MMP-2, which may map to a predicted GRE between -1510 and -1386 bp of the MMP-2 promoter. Additionally, Sp1, a known transcriptional activator of MMP-2 was decreased following corticosterone treatment. This study provides new insights into the mechanisms by which pathophysiological levels of endogenous glucocorticoids may exert angiostatic effects.
Adiponectin (Ad) is linked to various disease states and mediates antidiabetic and anti-inflammatory effects. While it was originally thought that Ad expression was limited to adipocytes, we demonstrate here that Ad is expressed in mouse skeletal muscles and within differentiated L6 myotubes, as assessed by RT-PCR, Western blot, and immunohistochemical analyses. Serial muscle sections stained for fiber type, lipid content, and Ad revealed that muscle fibers with elevated intramyocellular Ad expression were consistently type IIA and IID fibers with detectably higher intramyocellular lipid (IMCL) content. To determine the effect of Ad on muscle phenotype and function, we used an Ad-null [knockout (KO)] mouse model. Body mass increased significantly in 24-wk-old KO mice [+5.5 ± 3% relative to wild-type mice (WT)], with no change in muscle mass observed. IMCL content was significantly increased (+75.1 ± 25%), whereas epididymal fat mass, although elevated, was not different in the KO mice compared with WT (+35.1 ± 23%; P = 0.16). Fiber-type composition was unaltered, although type IIB fiber area was increased in KO mice (+25.5 ± 6%). In situ muscle stimulation revealed lower peak tetanic forces in KO mice relative to WT (−47.5 ± 6%), with no change in low-frequency fatigue rates. These data demonstrate that the absence of Ad expression causes contractile dysfunction and phenotypical changes in skeletal muscle. Furthermore, we demonstrate that Ad is expressed in skeletal muscle and that its intramyocellular localization is associated with elevated IMCL, particularly in type IIA/D fibers.
From Research to Practice| May 15 2023 Current Trends and Strategies for Exercise in Diabetes Susana R. Patton 0000-0002-8902-6965 ; Susana R. Patton Diabetes Spectrum Associate Editor Search for other works by this author on: This Site PubMed Google Scholar Michael C. Riddell 0000-0001-6556-7559 Michael C. Riddell Guest Editor Corresponding author: Michael C. Riddell, mriddell@yorku.ca Search for other works by this author on: This Site PubMed Google Scholar Corresponding author: Michael C. Riddell, Diabetes Spectr 2023;36(2):100–103 https://doi.org/10.2337/dsi22-0019 PubMed: 37193211 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Cite Icon Cite Get Permissions Citation Susana R. Patton, Michael C. Riddell; Current Trends and Strategies for Exercise in Diabetes. Diabetes Spectr 1 May 2023; 36 (2): 100–103. https://doi.org/10.2337/dsi22-0019 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsDiabetes Spectrum Search Advanced Search Regular physical activity, which includes structured sessions of exercise for fitness, health, and/or enjoyment, plays an important role in the daily management of diabetes (1,2). Regular sessions of moderate-to-vigorous physical activity (MVPA) and the avoidance of prolonged sitting time are regarded as one of the Association of Diabetes Care & Education Specialists' ADCES7 self-care behaviors for optimal diabetes self-management—specifically "being active" (3). The World Health Organization (WHO) defines "physical activity" as any physical movement supported by skeletal muscles that increases energy use (4). This can include activities performed as part of leisure time, traveling, or an individual's job. By contrast, "exercise" represents a subset of physical activity. All forms of physical activity count toward the American Diabetes Association (ADA) and WHO goal of at least 150 minutes of MVPA per week (2,4). Regular physical activity and exercise yield... You do not currently have access to this content.
<b>Objective</b>: To compare glucose control with hybrid closed loop (HCL) when challenged by moderate-intensity exercise (MIE), high-intensity intermittent exercise (HIE) and resistance exercise (RE) while profiling counter-regulatory hormones, lactate, ketones, and kinetic data in adults with type 1 diabetes. <p><b>Methods</b>: <a>Open-label multisite randomized crossover trial. </a><a>Adults with type 1 diabetes undertook 40 min of HIE, MIE, and RE in random order while using HCL (Medtronic 670G) with a temporary target set 2 hours prior to and during exercise and 15g carbohydrates if pre-exercise glucose was <126mg/dL, to prevent hypoglycemia.</a> Primary outcome was median (IQR) continuous glucose monitoring (CGM) time-in-range (TIR, 70-180 mg/dL) for 14 hours post-exercise commencement. Accelerometer data and venous glucose, ketones, lactate, and counter-regulatory hormones were measured for 280 min post-exercise commencement. </p> <p><b>Results</b>: Median TIR was 81% [67, 93]%, 91% [80, 94]%, and 80% [73, 89]% for 0-14 hours post-exercise commencement for HIE, MIE and RE, respectively (n=30), with no difference between exercise types (MIE v HIE; p=0.11, MIE v RE p=0.11, HIE v RE p=0.90). Time-below-range was 0% for all exercise bouts. For HIE and RE compared with MIE, there were greater increases respectively in noradrenaline (p=0.01, p=0.004), cortisol (p<0.001, p=0.001), lactate (p£0.001, p£0.001) and heart rate (p=0.007, p=0.015). During HIE compared with MIE, there were greater increases in growth hormone (p=0.024). </p> <p><b>Conclusions</b>: Under controlled conditions, HCL provided satisfactory glucose control with no difference between exercise type. Lactate, counter-regulatory hormones, and kinetic data differentiate type and intensity of exercise, and their measurement may help inform insulin needs during exercise. However, their potential utility as modulators of insulin dosing will be limited by the pharmacokinetics of subcutaneous insulin delivery. </p>
