One day you go to the doctor and he says “you have diabetes”, as if you just got it. WRONG! You’ve been working on it for years – many, many years. Your sugar ever so slowly starts to climb (your body can’t keep up) until it reaches the level that your regular doctor finally tells you’ve hit the dreaded “D”-level. But as you’ve heard, exercise can make a huge difference – but how much of a difference?
This study, while small, has profound implications. Hang in there while I try to explain it – it’s a little complicated if you are unfamiliar with the particulars. Some definitions first.
Think of an oral glucose tolerance test (OGGT) as drinking a sickeningly sweet drink all at once, then checking blood sugar levels an hour and two later. Insulin sensitivity is how relatively self-explanatory – how sensitive your body is to insulin (hint – it should be really sensitive), and type 2 diabetes is all about insulin insensitivity (also known as glucose intolerance).
The study takes young (average age 35) people who are sedentary or moderately active, normal to slightly overweight, with no evidence of diabetes and tests them with OGGTs. First, they’re asked to sit around for 4 days and then they’re tested, giving us some blood sugar and insulin levels. They are then asked to do an easy jog for 30 minutes and are tested again on the following day.
The findings are profound – a significant drop in blood sugars and insulin levels after the simple jog. That’s after 1 jog! What if someone actually did REGULAR exercise!!!
Research studies have shown that a full 25% of normal, skinny, healthy, active youth (college age) already show evidence of being on the way to diabetes. I’m sure some of these subjects were among the group that would have qualified, but if we can’t know who’s at risk, and we have an opportunity to seriously impede progress to a life-threatening condition, why wouldn’t we take advantage!?!
But hey, here I am talking about exercise again. Go figure.
A Single Jog Can Improve Glucose Metabolism in Young Adults
TOPLINE:
In healthy young adults, a single 30-minute bout of outdoor aerobic exercise significantly reduces fasting and 1-hour glucose levels during an oral glucose tolerance test (OGTT) the next day and improves insulin sensitivity.
METHODOLOGY:
Recent studies have identified 1-hour post-load glucose concentration during an OGTT as a specific and early predictor of diabetes, and exercise has long been known for its metabolic benefits in people with and without diabetes.
The researchers investigated the effect of a single bout of aerobic exercise on 1-hour post-load glucose levels during an OGTT in 32 young, healthy, normal-weight or marginally overweight individuals (mean age, 35 years; 14 women and 18 men) with a sedentary or moderately active lifestyle.
The participants underwent an initial OGTT after at least 4 days of physical inactivity, followed by a second OGTT the day after a single 30-minute bout of aerobic exercise.
The exercise session consisted of a light jog for 30 minutes, monitored using a metabolic holter to quantify energy expenditure and exercise intensity. The participants did not undertake any exercise outside the lab sessions.
Blood glucose levels were measured, and insulin sensitivity and secretion were estimated using surrogate indices derived from OGTT glucose and insulin assays, including the Matsuda index, oral glucose insulin sensitivity (OGIS) index, and quantitative insulin sensitivity check index, as well as the homeostasis model assessment (HOMA) of insulin resistance and of beta-cell function (HOMA-B).
TAKEAWAY:
A single 30-minute bout of aerobic exercise significantly reduced 1-hour post-load glucose levels from 122.8 mg/dL at baseline to 111.8 mg/dL ( P = .03) the day after exercise.
Postexercise insulin levels also were significantly lower 1 hour after glucose load, decreasing from 57.4 IU/mL at baseline to 43.5 IU/mL the day after exercise ( P = .01).
Insulin sensitivity improved significantly after exercise, as indicated by increases in the Matsuda index ( P = .02) and OGIS index ( P = .04), along with a reduction in insulin resistance ( P = .04).
The study found a trend toward increased beta-cell function the day after an exercise bout, as indicated by a nonsignificant increase in HOMA-B from 144.7 at baseline to 167.1 after exercise.
IN PRACTICE:
“Improvement in 1-hour post-load plasma glucose following a single session of aerobic physical activity suggests that exercise could have a direct effect on T2D [type 2 diabetes] risk and cardiovascular risk,” the authors wrote.
SOURCE:
The study was led by Simona Moffa, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, and Gian Pio Sorice, University of Bari "Aldo Moro," Bari, Italy. It was published online in the Journal of Endocrinological Investigation .