Lung function at rest and during exercise in patients with newly-diagnosed early-onset type 2 diabetes mellitus: a pilot study

Tests of lung and heart function at rest and during exercise. All of the tests below are conducted on the same day and are anticipated to take about 3.5 hours. Tests conducted at rest: 1. Blood sampling. 20 mls of venous blood will be sampled from the antecubital fossa (near elbow crease) by inserting a small butterfly catheter. Note that you are required to fast overnight (and patients with T2D are also required to delay the morning diabetes medication). A light breakfast and diabetes medications will be taken as soon as blood has been sampled. 2. Lung function tests. Measurement of how quickly you can blow out after a deep breath (spirometry); lung volumes (plethysmography); and breathing in and blowing out against a resistance, as hard as you can (to test the strength of your breathing muscles). All these tests require you to breathe through a mouthpiece and wear a noseclip. You will be asked to sit on a chair inside a booth (about the size of a telephone box) that has a glass window and a glass door. There is the possibility that you may feel claustrophobic, however, the door can be opened by you from the inside at any time. In total, these tests will take 20 minutes, at most. 3. Anthropometry - measurement of your height, weight and waist circumference. Two exercise tests will be performed (after screening for suitability to undertake intense exercise): 1. Incremental, symptom-limited exercise test. This test involves exercising on a stationary bike and you will be asked to pedal until you are too tired to continue or you request that the test be stopped or the researchers decide to stop the test – whichever comes first. This test will be supervised by a medical officer. This is an incremental test which means that the load (or resistance) that you are pedaling against will get harder every minute. During this test you will wear a noseclip and breathe through a mouthpiece so we can measure the amount and composition of the air that you breathe out; you will have electrodes attached to your chest to allow us to monitor heart rate and rhythm; you will have a small infrared sensor clipped lightly on one ear lobe to measure blood oxygen saturation; and you will have a blood pressure cuff attached to one arm. None of these attachments should cause you any discomfort. Towards the end of this test you can expect your muscles to feel tired and you will be breathing quite heavily and perspiring. This test usually takes, at most, about 10-12 minutes once you start pedaling. 2. Submaximal exercise test (incorporating cardiorespiratory tests to non-invasively measure your lungs’ diffusing capacity and lung blood flow): this test will be conducted on a stationary bike. In this test you will pedal at three different workloads (30, 60 and 90% of the final load you achieved in the first exercise test) for four minutes at each load. This test will not feel as hard as the symptom-limited peak exercise test. The same equipment that was attached to you in the incremental test will be used in this test too. In addition, we will perform the following procedures at rest and during exercise: At rest and at the end of testing at each workload we will ask you to breathe out fully, then breathe in one full breath of a gas mixture containing minute amounts of carbon monoxide, methane and acetylene (0.3%) and normal amounts of oxygen and nitrogen. We will then ask you to breathe out slowly. By measuring the concentration of gases in your exhaled breath, we will calculate lung blood flow and the capacity of your lung to exchange gas (diffusing capacity). This is a standard test used world-wide and there are no side-effects in breathing in the tiny quantities of carbon monoxide, methane and acetylene we will use for this study. This submaximal test will take about 16-20 minutes, inclusive of the rest period before starting to cycle. We will provide you with morning tea after all testing has finished. All volunteers will be reimbursed for travel costs ($50).