Diet is the cornerstone of treatment of type 2 DM. Simple initial advice for calorie restriction and avoidance of sweet foods and drinks can lead to symptomatic improvement and a fall in blood glucose levels before any reductions in body weight are detectable. More detailed advice is then required to formulate a long-term strategy. The main goal is to correct obesity as weight loss will improve blood glucose control, lower blood pressure and lower blood lipid concentrations, all of which may be expected to improve the prognosis for patients with type 2 DM. A diet similar to that advised for patients with type 1 DM is recommended with special emphasis on lowered fat intake and reduced energy intake.
Dietary failure is common in the treatment of overweight associated with type 2 DM. At the outset, avoidance of fat in the diet must be stressed and it is important to define realistic body-weight targets and rates of weight loss. Discussion of ideal body weight from actuarial tables is usually met with dismay and discourages patients. A rate of weight loss of about 0.5 kg/week is realistic. Progressive long-term weight loss is rarely achieved. Positive discussion and encouragement are to be recommended as outright censure and accusations of 'cheating' are unhelpful. The use of orlistat (Xenical®, Roche) which reduces intestinal fat absorption may help some patients with their weight loss program. An increase in regular exercise and avoidance of smoking are also advisable.
Taking exercise has been a recommendation in patients with type 2 DM for a very long time. The corollary is that type 2 DM is more likely to occur in populations that are physically sedentary. Thus, patients with type 2 DM may be innately resistant to the suggestion that they take physical exercise and this frequently presents a challenge to diabetes educators and physicians. From a meta-analysis of clinical trials examining the effect of exercise interventions on glycemic control and BMI in type 2 DM, subjects in the intervention group achieved a glycosylated hemoglobin (HbA1c) value that was 0.66% lower than that of the control group. Interestingly, there was no difference in body weight between the exercise and the control group suggesting that exercise has a beneficial effect independent of a reduction in body weight.
An inverse association between mortality and physical activity has been demonstrated in men with type 1 DM. Regular exercise has also been shown to lead to reduced morbidity and mortality in type 2 DM. Furthermore, as discussed at more length elsewhere (vida supra), exercise has been shown to reduce the risk of developing type 2 diabetes in people with impaired glucose tolerance. Exercise improves insulin sensitivity in both those with impaired glucose tolerance and diabetes - both type 1 and type 2.
Specific recommendations and guidelines for exercise by diabetic patients have been published by the American Diabetes Association and it is important to stress that even non-strenuous exercise such as regular walking ('walking the malls') is beneficial. Prescriptions for exercise should be tailored to the individual patient taking into account comorbidity and patient choice. Patients are not likely to continue with sports or exercises that they do not enjoy - in practical terms this may create real problems for many patients and their advisors.
For patients with type 1 DM, a reduction in insulin dosage is often required before exercise with dose reductions of 30-50% being common, although individuals' response to exercise may differ and the necessary dose reduction has to be determined by trial and error using blood glucose measurements before, during and after exercise. It will also be affected by the type, duration and intensity of the physical activity. In type 2 DM, exercise does not usually cause hypoglycemia but may do so in those patients taking oral sulfonyl-ureas or, of course, being treated with insulin. In normal subjects, insulin secretion declines during moderately intense aerobic exercise to compensate for increased muscle insulin sensitivity. In type 1 DM, as all insulin is exogenous, this cannot occur and this, in combination with increased insulin absorption if the insulin is injected into a limb which is subsequently exercised and the use of intermediate or long-acting insulin, often leads to hyperinsulinemia and hypo-glycemia if corrective actions are not taken as indicated above. Paradoxically, if hypoinsulinemia occurs, especially during intensive exercise, increased glucose production, decreased peripheral glucose uptake and increased levels of counter-regulatory hormones leading to lipid breakdown and ketogenesis can cause the development of both hyperglycemia and ketosis.
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Studies show obesity may soon overtake tobacco as the leading cause of death in America. Are you ready to drop those extra pounds you've been carrying around? Awesome. Let's start off with a couple positive don't. You don't need to jump on a diet craze and you don't need to start exercising for hours each day.