The effect of nutrition and exercise in addition to hypoglycemic medications on HbA1C in patients with type 2 diabetes mellitus: a systematic review protocol

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Abstract

Review question/objective

Review question: what is the effect of diet and exercise in addition to hypoglycemic medications versus hypoglycemic medications alone on the HbA1C levels in adults with a diagnosis of type 2 diabetes mellitus?

Review question/objective

The objective of this review is to identify the effectiveness of nutrition and exercise in addition to hypoglycemic medications compared to usual care on HbA1C levels in adults with the diagnosis of type 2 diabetes mellitus.

Background

Diabetes is a group of diseases which involve elevated blood glucose levels; defects in insulin production and or action and can lead to complications and early death.1 Diabetes is a chronic disease characterized by hyperglycemia as a result of the body's poor insulin production or resistance to insulin.2 Type 2 diabetes mellitus (DM) which was formally known as non-insulin dependent diabetes mellitus (NIDDM) is the most common type and accounts for more than 90% of all cases of diabetes, worldwide. 3

Background

Type 2 DM commonly begins as resistance to insulin when the cells are unable to utilize it properly, therefore increasing the demand on the pancreas which may not be able to meet the increased need.1 There is an association of type 2 DM with older age, obesity, family history of diabetes, history of gestational diabetes, impaired glucose metabolism, lack of physical activity as well as race and ethnicity.1

Background

The criteria for diagnosis of type 2 DM may vary slightly depending on the source referenced. The authors of this paper recognize the World Health Organization's (WHO) criteria for the diagnosis of type 2 DM can be any one of the following: a fasting plasma glucose (FPG) of 126 mg/dl (7.0 mmol/l), an oral glucose tolerance test with FPG of 126mg/dl (7 mmol/l) and/or two-hour blood glucose of 200mg/dl (11 mmol/l) or a HbA1C (glycated hemoglobin) of 6.5% (48 mmol/mol) or a random blood glucose of 200 mg/dl (11mmol/l) with the presence of symptoms of diabetes.4

Background

Diabetes has been linked to a lower quality of life, increased morbidity related to vascular complications as well as reduced life expectancy.2 Studies have shown that improved glycemia control benefits patients with type 2 DM to prevent microvascular complications.1 The focus of treatment is on the optimal control of blood sugar although there is some debate as to the exact number which defines optimal control. The International Diabetes Foundation (IDF) uses a goal of HbA1C of 7% or less to determine treatment effect4 while the American Association of Clinical Endocrinologists and the European Association for the Study of Diabetes have recommended a lower haemoglobin A1c target of less than 6.5%.5

Background

Treatment of type 2 DM often includes following a healthy diet and exercise routine, reduction of excess weight and taking prescribed medications; all aid in the maintenance of blood glucose control.1 These interventions should be conducted under the supervision of a healthcare professional to prevent other complications. Management of type 2 DM and its related complications is complex because it is a slow, progressive, degenerative microvascular disease. Insulin levels are altered by certain forms of exercise and in people with diabetes; in addition a failure to adequately adjust medications or carbohydrate supplementation can result in inappropriate swings in blood glucose levels, either too low or too high, depending on the factors involved.6

Background

Diabetes is a growing problem both nationally and worldwide. There are 25.8 million adults and children in the US that have diabetes, that is 8.3% of the population.7 Throughout the world 347 million people are diagnosed with diabetes3 and it was estimated that 3.4 million deaths in 2004 were related to high blood sugar.2 By the year 2030 the WHO predicts that worldwide, twice as many deaths will be a direct result of diabetes as seen in 2005.3 Diabetes is a major contributor to heart disease and stroke as well as blindness, kidney failure and lower limb amputation in the United States and is the 7th leading cause of death.8 According to the Centers for Disease Control and Prevention (CDC), the risk of microvascular disease can decrease by as much as 40% when the HbA1C is decreased by 1 percentage point.9 It is essential for healthcare providers to best support their patients with type 2 DM to vital to achieve optimal control of their glucose levels to reduce the risk of complications.

Background

After reviewing the literature, it is evident that diabetes crosses all cultures and nationalities. According to the CDC the adjusted age population differences with respect to the 2007 to 2009 national survey for ages 20 years and older, indicate that 7.1% of non-Hispanic whites; 8.4% of Asian Americans; 11.8% of Hispanics; 12.6% of non-Hispanic blacks had been diagnosed with diabetes; and of Hispanics, rates were 7.6% for both Cubans and for Central and South Americans; 13.3% for Mexican Americans; and 13.8% for Puerto Ricans.1

Background

People with diabetes cost the health care system twice as much in medical expenses as those without the disease.9 Diabetes comes at the cost of 245 billion dollars in the United States in 2012.7 Zhang P, Zhang X, Betz Brown J, et al. predicted in 2010 that global health expenditures to prevent and treat diabetes and its complications will total at least US dollar (USD) 376 billion. By 2030, this number will exceed some (USD) 490 billion.10 Expenditures on healthcare related to diabetes are advancing at an enormous rate and the global economy cannot afford to maintain these expenses.

Background

It has been shown in the literature that type 2 DM patients generally take more than two medications for lowering their blood glucose and often encounter unsuccessful glycemia in many cases.10 Among those Americans diagnosed with both type 1 and type 2 diabetes 12% were on insulin alone, 58% take only oral medications and 14% take both insulin and oral medications.9 One study reports that physicians openly recommend patients to take high doses of oral hypoglycemic agents (OHA) and additional insulin therapy rather than the reversible approach such as lifestyle modification to effectively control glucose level.11 This recommendation may be time saving but not effective in reducing healthcare costs.

Background

Management of glycemia control in patients with type 2 DM presents an enormous challenge to those in healthcare and to further complicate matters, research varies on its recommendations. Considering combination modalities to target different pathogenic mechanisms and manage fasting and postprandial blood glucose levels is essential.5 The CDC states that health outcomes can be improved by a healthy diet and being active as well as monitoring blood sugar.8 It has been shown that lifestyle management through weight loss and increase in activity decreased the incidence of diabetes by 58% in those identified as high possibility for diabetes in a preventative study known as the Diabetes Prevention Program (DPP).9 Weight loss and increased physical activity has also shown to prevent or delay type 2 DM in those who have been identified as prediabetic.1

Background

The management of type 2 DM may be better optimized even on medication with the addition of a healthy nutrition plan and exercise. It is recommended that patients diagnosed with type 2 DM receive assistance and guidance to make lifestyle modifications to improve control of blood glucose, even when on medication.4 The recommended treatment of diabetes includes diet, insulin and oral medications as the foundation of diabetic management. Patient education and self-care practices are an important aspect of the plan. Often those with type 2 DM control their blood glucose by participating in a healthy diet and exercise program, losing weight and taking oral anti-glycaemia medications. Others require taking insulin in addition to controlling their blood glucose levels.1,5

Background

The American Diabetes Association and the European Association for the Study of Diabetes published an algorithm for managing type 2 DM. The algorithm recommends initiation of metformin at diagnosis along with lifestyle modification that includes medical nutrition therapy (MNT) and additional oral hypoglycemic agents or insulin if the HbA1c goal of less than 7% is not met or maintained.5 Combination therapy is often needed and insulin is added to the algorithm to attain the HbA1c goal. MNT and physical activity enhance the actions of hypoglycemic medication in the regimen.5

Background

Although definitive data on the benefits of long-term weight loss to reduce risk for clinical complications of diabetes are pending, the evidence-based nutrition recommendations of the American Diabetes Association emphasize the importance of weight management as a key element of medical nutrition therapy for diabetes.12

Background

Exercise along with dietary intervention represents first-line therapy for DM.6 As a result of regular physical activity, insulin sensitivity is increased, pharmacotherapy is improved, blood glucose and fat content is decreased, and there is increased muscle mass in addition to cardiovascular health and function.13 For individuals with type 2 DM, weight loss may be achieved through a low-calorie diet in combination with exercise.14 A negative balance of caloric intake and expenditure is necessary for weight loss however, adequate caloric intake is important so one can exercise safely. Well-balanced meals as recommended by the American Diabetes Association two to three hours before planned exercise of aerobic type greater than 30 minutes, facilitates the maintenance of adequate blood glucose levels during exercise.14

Background

Postprandial hyperglycemia is a largely underestimated problem in type 2 DM treatments. Despite the continued use of blood glucose-lowering medication and the provision of a healthy, well-balanced diet, type 2 DM patients were shown to experience hyperglycemia episodes.15 Van Dijk, Tummers, Stehouwer, Hartgens and Van Loon showed that 30 minutes of moderate-intensity exercise substantially reduces the prevalence of hyperglycemia throughout the subsequent day. A single bout of exercise reduced the prevalence of hyperglycemic episodes by nearly two hours while average blood glucose concentrations throughout the subsequent day were reduced by 0.8 mmol/L: from 9.1 to 8.3 mmol.15

Background

A study by Wagner, Degerblad, Thorell, Stajl, Bavenholm demonstrated that in subjects with mild type 2 DM, exercise training improved insulin sensitivity but had no effect on glycemia control, however, when exercise training was combined with acarbose treatment (median dose 245 mg/day), glycemia control was significantly improved as reflected by a decrease in A1C level and fasting plasma glucose concentration.16 Another study showed that obese individuals with type 2 DM on diet therapy alone or diet and sulphonylurea with post absorptive hyperglycemia and normal basal insulin, show a significant lowering in glycemia during moderate exercise. This study further reported that exercise could decrease circulating glucose levels and increase insulin sensitivity in patients with type 2 DM. The potential importance of exercise as an adjuvant therapy is warranted for this patient population.14

Background

The literature supports diet as an important component when managing type 2 DM. Lazarou, Panagiotakos and Matalas (2010) suggest that a diet such as the Mediterranean Diet may be protective against the development of diabetes as well as efficient in its control, but more evidence is required.17 The use of metformin and liraglutide treatment in conjunction with a diet low in carbohydrate for patients with advancing disease who were scheduled to switch or increase their insulin treatment was shown to be effective in gaining control and actually showed a significant treatment effect with most participants achieving HgbA1C levels less than 7% in a proof-of-principle study.18

Background

Kim, Jung, Jung, Kim and Hahm reported that 77.8% of patients who demonstrated decreased HbA1C level indicated that they actually carried out the lifestyle modification. Over 90% patients who followed diet and exercise control had a decrease of HbA1c. A decrease of less than 7%, suggested again that counseling and education about lifestyle modification are very important in type 2 DM patients who are taking medications. This can improve the glucose level of patients without additional medication.11 While it is well known that insulin is a valid treatment, Kim et al. suggest that there are some alternative possible ways to improve the glucose levels by re-emphasizing the lifestyle modification in patients who are reluctant to initiate treatment with additional medications.11

Background

The intervention of behavior modification with the intent to lose and maintain 7% of weight and increase physical activity over a 12 month period demonstrated a lower usage of maintenance medications and costs for diabetes care, hypertension and hyperlipidemia as described in a study by Matvienko and Hoehns (2009). It is suggested that these results may be biased, the study had no control group and lacked cultural diversity, but there have been other studies which had comparable results.19 Exercise has been shown to be equally effective to reduce the incidence of hyperglycemia and improve glycemia control in patients with type 2 DM, both insulin and non-insulin dependent, either in short bouts daily or longer bouts every other day.18

Background

To date, there are no published systematic reviews specific to the intervention of exercise and diet in addition to hypoglycemic medications for improved HgbA1C for patients diagnosed with type 2 DM. The objective of this systematic review is to synthesize evidence related to diet and exercise for adult patients with type 2 DM who are currently taking hypoglycemic medications to determine if management should include diet and exercise to improve blood glucose. The evaluation outcome will be hemoglobin A1C of patients who follow specific diet and exercise protocols versus usual care. Usual care will be defined as hypoglycemic medication alone. Hypoglycemic medications will include both oral and injectables (insulin and non-insulin) for the purpose of this review.

Background

Our target population is adults with type 2 DM in primary care settings. The intervention is diet and exercise therapy in addition to hypoglycemic medications and the evaluation outcome will be the hemoglobin A1C.

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