The central dilemma of type 2 diabetes management is that the progressive, unremitting loss of beta-cell function that is the hallmark of type 2 diabetes begins before the clinical diagnosis of type 2 diabetes. Thus, for lifestyle modification to be truly effective long-term, we must recognize the potential for diabetes before its onset and implement effective change strategies that deal with and reverse processes leading to beta-cell loss. Although lifestyle management involving exercise and weight reduction may be effective, we do not know at what stage they must be started to have lasting impact. Otherwise, our current approaches delay but do not reverse the onset of diabetes.
Lifestyle interventions have been shown to reduce the incidence of diabetes in persons at high risk.1 Likewise, lifestyle modification after diabetes is diagnosed is always beneficial in terms of reducing medication requirements and facilitating glucose control. However, there are limits to the effectiveness of lifestyle manipulations. Weight is rarely lost long-term. In the short run, weight loss may occur with low carbohydrate or low-fat, calorie-restricted diets.2 In the 10-year follow-up to the Diabetes Prevention Program (DPP) Outcomes Study, individuals in the lifestyle group initially lost a mean of approximately 15 pounds by 1 year, but gradually regained weight.1On completion of the study, these participants still weighed approximately 4 pounds less than at the time of randomization.1
The DPP Research Group demonstrated that lifestyle intervention can result in a 58% reduction in the risk of diabetes.3 The researchers more recently examined behavioral factors related to achieving weight loss and physical activity goals met by the DPP lifestyle participants.4 Meeting the exercise goal was found to be positively related to the achievement of weight loss.4 Regular daily exercise helps increase calorie deficits, but this can be wearing on joints and muscles that are not used to such exercise and may lead to orthopedic interventions.
The most that can be reasonably expected in terms of improved glycemic control in the reported US studies is that few trials reached the target hemoglobin A1c of 6.6%.5 In part, this reflects the long-term patient difficulty in complying with the lifestyle modification, and in part it reflects the declining beta-cell function. Regardless, berating patients for primary or secondary lifestyle failure amounts to creating a vicious circle of depression and physician avoidance, which further undermines the utility of lifestyle modifications.
Above all, reasonable expectations and a realization of the limitations of lifestyle intervention must be kept in mind when dealing with patients with diabetes. After all, if lifestyle modification was so easy and appealing to this patient population, it would likely have been implemented already, because of social pressures.
In patients with chronic kidney disease (CKD), unique factors complicate the use of lifestyle modification for this comorbid condition. These factors include, but are not limited to, the nature of the diet. The most widely used and effective weight-loss diets in these patients include high-protein and low-carbohydrate or low-fat contents. Unfortunately, such diets may well worsen albuminuria2 and, likely, renal function as well.
The low-protein, high-carbohydrate diets favored by kidney specialists tend to exaggerate postprandial hyperglycemia and worsen overall diabetes control. Added salt is often used to flavor low-calorie foods. Yet salt worsens hypertension and may undermine the same low blood pressure goals of diabetes
management in patients with concomitant kidney disease. Finally, there is no evidence that impact exercises cause CKD or progression to CKD; therefore, there is likely no need for patients with CKD to avoid them.2
As with many other treatment options, there is no one ideal approach to lifestyle modification for all patients with type 2 diabetes. It is even more challenging regarding the spectrum of choices, which are more limited in patients with type 2 diabetes and comorbid CKD.
References
- Diabetes Prevention Program Research Group. 10-year follow-up of diabetes incidence and weight loss in the diabetes prevention program outcomes study. Lancet. 2009;374:1677-1686.
- American Diabetes Association. Standards of medical care in diabetes—2010. Diabetes Care. 2010;33(suppl 1):11-61. Erratum in: Diabetes Care. 2010;33:692.
- Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346:393-403.
- Diabetes Prevention Program Research Group. Achieving weight and activity goals among diabetes prevention program lifestyle participants. Obes Res. 2004;12:1426-1434.
- The Look AHEAD Research Group. Reduction in weight and cardiovascular disease risk factors in individuals with type 2 diabetes. Diabetes Care. 2007;30:1374-1383.