Original articleGender differences in the onset of diabetic neuropathy
Introduction
Type 2 diabetes mellitus (DM2), a common metabolic disorder characterized by hyperglycemia, is caused by genetics, environmental factors, and lifestyle choices. It is also characterized by insulin resistance, diminished insulin secretion, and increased hepatic glucose production (Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 1997, Kuzuya et al., 2002). The metabolic abnormalities that occur with DM2 cause alterations in several organ systems, place physical and emotional burdens on individuals with DM2, and negatively impact the health care system (Caro et al., 2002, Expert Committee on the Diagnosis and Classification of Diabetes Mellitus, 1997, Gordois et al., 2003, Shearer et al., 2003).
The metabolic alterations linked to DM result in chronic complications that account for much of the morbidity and mortality associated with this disorder (Kuzuya et al., 2002, UK Prospective Diabetes Study Group, 1998). These complications, primarily vascular in nature, may be divided into macrovascular (Andersson & Svardsudd, 1995, Dyck et al., 1995, Wandell, 1999) and microvascular (Booya et al., 2005, Bruce et al., 2005, Dyck et al., 1995, Henry, 1996, Wandell, 1999) complications. Macrovascular complications include cerebrovascular disease, coronary artery disease, and peripheral vascular disease (Gaster & Hirsch, 1998, Maser et al., 1989, Wandell, 1999), whereas microvascular complications include neuropathy, retinopathy, and nephropathy (McClean et al., 2005, Wandell, 1999).
The risk for microvascular diabetic neuropathy is directly proportional to the duration of hyperglycemia and that of diabetes (Booya et al., 2005, Bruce et al., 2005, Klein et al., 1996, Kuzuya et al., 2002). A study that compared 110 patients with DM and those without neuropathy found that hyperglycemia was the only modifiable risk factor for diabetic neuropathy. Furthermore, the study found that patients with poor glycemic control had a 0.3 times greater risk for the development of diabetic neuropathy (Booya et al., 2005). Most individuals with DM2 remain asymptomatic before being diagnosed. Many have manifestations of one or more diabetic complications at the time of diagnosis (Booya et al., 2005, Harris et al., 1992, Kramer et al., 2005, UK Prospective Diabetes Study Group, 1998); the number increases to as many as 50% of all individuals throughout the course of the disease (Pirart, 1977).
Treatment of diabetic neuropathy revolves around improved glycemic control, which may help improve nerve conduction velocity (Dyck et al., 1995, Gaster & Hirsch, 1998, Kramer et al., 2005, Tolle et al., 2006). Improved glycemic control has been shown to slow down—and possibly halt—the progression of diabetic neuropathy (Ohkubo et al., 1995, Tolle et al., 2006). In one study, intensive insulin therapy decreased the appearance of neuropathy by 69%, as evidenced by nerve conduction testing at a 5-year follow-up examination (Diabetes Control and Complications Trial Research Group, 1993). Despite adequate glucose control, the symptoms associated with neuropathy may persist. These symptoms include pain, hyperesthesia, paresthesia, allodynia, and altered sense of position (Gordois et al., 2003, Ohkubo et al., 1995). This persistence may decrease quality of life and increase the frequency of hospital and physician visits among patients (Gordois et al., 2003, UK Prospective Diabetes Study Group, 1998). Gordois et al. estimated that among the 10.27 million individuals with DM2 in the United States, $10.15 billion is expended annually in the treatment of diabetic neuropathy and its complications. As a result, early prevention of the complication of diabetic neuropathy is imperative for the health and well-being of these patients; it may also reduce the health care burden that these patients will inevitably incur (Caro et al., 2002, Gordois et al., 2003).
Early prevention may lie in identifying risk factor profiles for diabetic neuropathy. One such risk factor is total hyperglycemia exposure (Booya et al., 2005, Bruce et al., 2005, Klein et al., 1996, Kuzuya et al., 2002). Gender may also be an important factor in the development of diabetic neurologic complications. Few studies have evaluated gender as a potential risk factor for the development of neurologic symptoms in patients with diabetes (Albers et al., 1996, Booya et al., 2005, Brown et al., 2004, Diabetes Control and Complications Trial Research Group, 1993). These studies failed to either assess age at onset of diabetic neuropathic symptoms (Albers et al., 1996, Booya et al., 2005, Brown et al., 2004) or separate DM1 from DM2 (Gregersen, 1967, Valensi et al., 1997). This study differs from studies in the current literature in that it sought to evaluate gender differences in the progression and age at onset of diabetic neuropathy complications in individuals with DM2.
Section snippets
Methods
This study, a retrospective chart analysis conducted at South Pointe Hospital, Warrensville Heights, OH, reviewed charts for all patients (age, ≥18 years) either admitted or seen as outpatients with International Classification of Diseases, Ninth Revision (ICD-9) codes for diabetes with neurologic manifestations (250.60 and 250.62) between January 2004 and January 2006. Exclusion criteria included being younger than 18 years and having major medical conditions such as cancer or AIDS. Three
Results
Three hundred seventy-six inpatient and outpatient charts were reviewed: 156 charts for male patients and 220 for female patients (41% and 59%, respectively). All patients included in the study had DM2, with 23% (n=86) requiring insulin therapy at the time of the study. Of all the patients, 69% were of African descent (n=260), 29.4% were Caucasians, and the final 1.6% were Asians. The population composition of the area where the hospital is located has a population distribution of 92% with
Discussion
Diabetic neuropathy is a serious complication of DM2 that presented 4 years earlier in the males as compared with the females in this study. Symptoms of diabetic neuropathy include pain, paresthesia, allodynia, hyperesthesia, and altered sense of position (Gordois et al., 2003, Ohkubo et al., 1995) and have a significant effect on quality of life; in addition, they present a sizable financial burden to patients and the health care system.
The present study found a significant difference in age
Conclusions
The investigation demonstrates that the males from this study developed diabetic neuropathic complications earlier than did the females. However, because an inner-city hospital was involved, it should be noted that the participants of the study are not representative of the US population and that the results may therefore not be generalizable to the entire United States. Combined with knowledge obtained from previous studies on gender and diabetic neuropathy, it may then be hypothesized that
Acknowledgments
We would like to thank the OUCOM CORE office, specifically Mr. Weiser and Dr. Brennan, for their help and support throughout the research process. Additionally, special thanks to Dr. Disa-Smith for her clinical expertise.
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