Glucocorticoids (GCs) are steroid hormones that exert important physiological actions on metabolism. Given that GCs also exert potent immunosuppressive and anti-inflammatory actions, synthetic GCs such as prednisolone and dexamethasone were developed for the treatment of autoimmune- and inflammatory-related diseases. The synthetic GCs are undoubtedly efficient in terms of their therapeutic effects, but are accompanied by significant adverse effects on metabolism, specifically glucose metabolism. Glucose intolerance and reductions in insulin sensitivity are among the major concerns related to GC metabolic side effects, which may ultimately progress to type 2 diabetes mellitus. A number of pre-clinical and clinical studies have aimed to understand the repercussions of GCs on glucose metabolism and the possible mechanisms of GC action. This review intends to summarize the main alterations that occur in liver, skeletal muscle, adipose tissue, and pancreatic islets in the context of GC-induced glucose intolerance. For this, both experimental (animals) and clinical studies were selected and, whenever possible, the main cellular mechanisms involved in such GC-side effects were discussed.

Recent antecedent hypoglycemia is a known source of defective glucose counterregulation in diabetes; yet, the mechanisms perpetuating the cycle of progressive α-cell failure and recurrent hypoglycemia remain unknown. Somatostatin has been shown to supress the glucagon response to acute hypoglycemia in rodent models of type 1 diabetes. We hypothesized that somatostatin receptor 2 antagonism (SSTR2a) would restore glucagon counterregulation and delay the onset of insulin-induced hypoglycemia in recurrently hypoglycemic, non-diabetic male rats. Healthy, male, Sprague-Dawley rats (n=39) received bolus injections of insulin (10 U/kg, 8 U/kg, 5 U/kg) on 3 consecutive days to induce hypoglycemia. On day 4, animals were then treated with SSTR2a (10 mg/kg; n=17) or vehicle (n=12) one-hour prior to the induction of hypoglycemia using insulin (5 U/kg). Plasma glucagon level during hypoglycemia was ~30% lower on day 3 (150±75 pg/ml; P<0.01), and 68% lower on day 4 in the vehicle group (70±52 pg/ml; P<0.001) compared to day 1 (219±99 pg/ml). On day 4, SSTR2a prolonged euglycemia by 25±5 min (P<0.05) and restored the plasma glucagon response to hypoglycemia. Hepatic glycogen content of SSTR2a-treated rats was 35% lower than vehicle controls after hypoglycemia induction on day 4 (vehicle: 20±7.0 vs SSTR2a: 13±4.4 µmol/g; P<0.01). SSTR2a treatment reverses the cumulative glucagon deficit resulting from three days of antecedent hypoglycemia in healthy rats. This reversal is associated with decreased hepatic glycogen content and delayed time to hypoglycemic onset. We conclude that recurrent hypoglycemia produces glucagon counterregulatory deficiency in healthy male rats, which can be improved by SSTR2a.

I n 2015/2016, a number of papers were published on the challenges of exercise management for patients living with diabetes. A big focus was on testing how the artificial pancreas might function during exercise, with or without activity announcements and the addition of glucagon. Moreover, several papers revealed barriers to exercise participation for people living with type 1 or type 2 diabetes. A few papers demonstrated that many of the tools for the preservation of glucose control during and after exercise in type 1 diabetes are not being used. This year, we selected 10 papers to highlight the field of exercise and diabetes, with an emphasis on ''technology'' rather than on the possible mechanisms for exercise action. Our initial search was restricted to human studies and primarily on studies in which patients with diabetes severed as subject participants. We screened over 150 papers on the topic that were found on Pubmed and other common search engines published between July 1, 2015 and June 30, 2016. The following 10 papers, we think, represent some of the highlights.

Associations of reallocating sitting time into standing or stepping with glucose, insulin and insulin sensitivity: a cross-sectional analysis of adults at risk of type 2 diabetes

Glucagon (GCN) helps prevent hypoglycemia when blood glucose levels drop; however, recurrent hypoglycemia attenuates GCN counterregulation to subsequent bouts of hypoglycemia. As somatostatin normally inhibits GCN secretion, we tested the hypothesis that a somatostatin receptor type 2 antagonist (SSTR2a), PRL-2903, improves GCN responses attenuated by recurrent hypoglycemia in healthy rats. Healthy male Sprague-Dawley rats (n=22) were made hypoglycemic on three consecutive days (days 1-3, blood glucose 1.7-2.2 mmol/L for ∼2 h) via exogenous insulin administration (10-, 8- and 5- U/kg of Humulin-R on days 1-3, respectively). GCN levels during hypoglycemia on day 3 were significantly lower than on day 1 (117±47 pg/mL vs. 184±77 [mean±SD] pg/mL; P=0.001), highlighting the role of recurrent hypoglycemia in counterregulatory failure. On day 4, rats were treated with either PRL-2903 (10 mg/kg IP; n=13) or vehicle (n=9) 1 h prior to the induction of hypoglycemia with 5 U/kg of R-insulin. GCN levels during hypoglycemia (i.e., glucose ≤3.5 mmol/L) were 2.5-fold higher (109±55 vs. 44±26 pg/mL; P=0.004) compared to vehicle, and time to reach hypoglycemia was 3.2-fold longer (64±45 vs. 20±10 min; P =0.001), with PRL-2903 pre-treatment. Interestingly, C-peptide levels were also lower (P=0.001) with PRL-2903 (0.35±0.22 ng/mL), compared to vehicle (0.63±0.21 ng/mL), inferring a lower insulin secretion during hypoglycemia with PRL-2903 treatment. In conclusion, our data suggests that SSTR2a improves GCN responses following recurrent hypoglycemia, and that this improvement may be associated with a reduction in insulin secretion in healthy rats. Therefore, SSTR2a treatment may be a useful therapeutic approach to improve GCN counterregulatory responses to hypoglycemia. Disclosure M. Riddell: Speaker's Bureau; Self; Medtronic. Consultant; Self; Eli Lilly and Company, JAEB Center For Health Research, Xeris Pharmaceuticals, Inc.. Research Support; Self; Insulet Corporation. Speaker's Bureau; Self; Insulet Corporation. Advisory Panel; Self; Sanofi. Speaker's Bureau; Self; Ascensia Diabetes Care. Stock/Shareholder; Self; Zucara Theraputics. Other Relationship; Self; JDRF. M. Jahangiriesmaili: None. E.R. Mandel: None. C.A. Greenberg: None. A.M. Pasieka: None. T. Teich: None. O. Chan: None. R.T. Liggins: Employee; Self; Zucara Therapeuytics, Inc..