Shah, Priyali

Rapidly changing dietary practices and a sedentary lifestyle have led to increasing prevalence of childhood obesity (5–19 yr) in developing countries recently: 41.8% in Mexico, 22.1% in Brazil, 22.0% in India, and 19.3% in Argentina. Moreover, secular trends indicate increasing prevalence rates in these countries: 4.1 to 13.9% in Brazil during 1974–1997, 12.2 to 15.6% in Thailand during 1991–1993, and 9.8 to 11.7% in India during 2006–2009. Important determinants of childhood obesity include high socioeconomic status, residence in metropolitan cities, female gender, unawareness and false beliefs about nutrition, marketing by transnational food companies, increasing academic stress, and poor facilities for physical activity. Childhood obesity has been associated with type 2 diabetes mellitus, the early-onset metabolic syndrome, subclinical inflammation, dyslipidemia, coronary artery diseases, and adulthood obesity. Therapeutic lifestyle changes and maintenance of regular physical activity through parental initiative and social support interventions are the most important strategies in managing childhood obesity. Also, high-risk screening and effective health educational programs are urgently needed in developing countries.

Although it is well established that glucagon-like peptide 1(7-36) amide (GLP-1) is a potent stimulator of insulin secretion, its effects on insulin action and glucose effectiveness are less clear. To determine whether GLP-1 increases insulin action and glucose effectiveness, subjects with type 2 diabetes were studied on two occasions. Insulin was infused during the night on both occasions to ensure that baseline glucose concentrations were comparable. On the morning of study, either GLP-1 (1.2 pmol x kg(-1) x min(-1)) or saline were infused along with somatostatin and replacement amounts of glucagon. Glucose also was infused in a pattern mimicking that typically observed after a carbohydrate meal. Insulin concentrations were either kept constant at basal levels (n = 6) or varied so as to create a prandial insulin profile (n = 6). The increase in glucose concentration was virtually identical on the GLP-1 and saline study days during both the basal (1.21 +/- 0.15 vs. 1.32 +/- 0.19 mol/l per 6 h) and prandial (0.56 +/- 0.14 vs. 0.56 +/- 0.10 mol/l per 6 h) insulin infusions. During both the basal and prandial insulin infusions, glucose disappearance promptly increased after initiation of the glucose infusion to rates that did not differ on the GLP-1 and saline study days. Suppression of endogenous glucose production also was comparable on the GLP-1 and saline study days during both the basal (-2.7 +/- 0.3 vs. -3.1 +/- 0.2 micromol/kg) and prandial (-3.1 +/- 0.4 vs. -3.0 +/- 0.6 pmol/kg) insulin infusions. We conclude that when insulin and glucagon concentrations are matched, GLP-1 has negligible effects on either insulin action or glucose effectiveness in people with type 2 diabetes. These data strongly support the concept that GLP-1 improves glycemic control in people with type 2 diabetes by increasing insulin secretion, by inhibiting glucagon secretion, and by delaying gastric emptying rather than by altering extrapancreatic glucose metabolism.