Nashville Diabetes Dentist

Diabetes mellitus type 2 or type 2 diabetes (formerly called non-insulin-dependent diabetes mellitus (NIDDM), or adult-onset diabetes) is a disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. It is often initially managed by increasing exercise and dietary modification, but medications are typically needed as the disease progresses. There are an estimated 23.6 million people in the U.S. (7.8% of the population) with diabetes with 17.9 million being diagnosed, 90% of whom are type 2. With prevalence rates doubling between 1990 and 2005, CDC has characterized the increase as an epidemic.

Traditionally considered a disease of adults, type 2 diabetes is increasingly diagnosed in children in parallel to rising obesity rates due to alterations in dietary patterns as well as in life styles during childhood.

Unlike type 1 diabetes, there is very little tendency toward ketoacidosis in type 2 diabetes, though it is not unknown. One effect that can occur is nonketonic hyperglycemia which also is quite dangerous, though it must be treated very differently. Complex and multifactorial metabolic changes very often lead to damage and function impairment of many organs, most importantly the cardiovascular system in both types. This leads to substantially increased morbidity and mortality in both type 1 and type 2 patients, but the two have quite different origins and treatments despite the similarity in complications.

Signs and symptoms

• Early symptoms may be nothing more than chronic fatigue, generalised weakness and malaise (feeling of unease)
• Excessive urine production
• Excessive thirst and increased fluid intake
• Blurred vision (typically from lens shape alterations, due to osmotic effects, e.g., high blood glucose levels)
• Unexplained weight loss
• Lethargy
• Itching of external genitalia
• Excessive bowel movements

Cause

Medical conditions

Although its incidence is far from universal, type 2 diabetes can arise from and be exacerbated by obesity, hypertension, elevated cholesterol (combined hyperlipidemia), and with the condition often termed Metabolic syndrome (it is also known as Syndrome X, Reavan’s syndrome, or CHAOS). Other causes include acromegaly, Cushing’s syndrome, thyrotoxicosis, pheochromocytoma, chronic pancreatitis, cancer and drugs. Additional factors found to increase the risk of type 2 diabetes include aging, high-fat diets and a less active lifestyle.

Genetics

Strong inheritable genetic connection in type 2 diabetes: having relatives (especially first degree) with type 2 increases risks of developing type 2 diabetes very substantially. In addition, there is also a mutation to the Islet Amyloid Polypeptide gene that results in an earlier onset, more severe, form of diabetes. About 55 percent of type 2 are obese —chronic obesity leads to increased insulin resistance that can develop into diabetes, most likely because adipose tissue (especially that in the abdomen around internal organs) is a (recently identified) source of several chemical signals to other tissues (hormones and cytokines). Other research shows that type 2 diabetes causes obesity as an effect of the changes in metabolism and other deranged cell behavior attendant on insulin resistance. However, genetics play a relatively small role in the widespread occurrence of type 2 diabetes. This can be logically deduced from the huge increase in the occurrence of type 2 diabetes which has correlated with the significant change in western lifestyle.

Medications

Drug induced hyperglycemia:

• Atypical Antipsychotics – Alter receptor binding characteristics, leading to increased insulin resistance.
• Beta-blockers – Inhibit insulin secretion.
• Calcium Channel Blockers – Inhibits secretion of insulin by interfering with cytosolic calcium release.
• Corticosteroids – Cause peripheral insulin resistance and gluconeogensis.
• Fluoroquinolones – Inhibits insulin secretion by blocking ATP sensitive potassium channels.
• Niacin – causes increased insulin resistance due to increased free fatty acid mobilization.
• Phenothiazines – Inhibit insulin secretion.
• Protease Inhibitors – Inhibit the conversion of proinsulin to insulin.
• Somatropin – May decrease sensitivity to insulin, especially in those susceptible.
• Thiazide Diuretics – Inhibit insulin secretion due to hypokalemia. They also cause increased insulin resistance due to increased free fatty acid mobilization.

Pathophysiology

Insulin resistance means that body cells do not respond appropriately when insulin is present. Unlike type 1 diabetes mellitus, insulin resistance is generally “post-receptor”, meaning it is a problem with the cells that respond to insulin rather than a problem with the production of insulin.

Other important contributing factors:

• increased hepatic glucose production (e.g., from glycogen -> glucose conversion), especially at inappropriate times (typical cause is deranged insulin levels, as those levels control this function in liver cells)
• decreased insulin-mediated glucose transport in (primarily) muscle and adipose tissues (receptor and post-receptor defects)
• impaired beta-cell function—loss of early phase of insulin release in response to hyperglycemic stimuli

This is a more complex problem than type 1, but is sometimes easier to treat, especially in the early years when insulin is often still being produced internally. Type 2 may go unnoticed for years before diagnosis, since symptoms are typically milder (eg, no ketoacidosis, coma, etc) and can be sporadic. However, severe complications can result from improperly managed type 2 diabetes, including renal failure, erectile dysfunction, blindness, slow healing wounds (including surgical incisions), and arterial disease, including coronary artery disease. The onset of type 2 has been most common in middle age and later life, although it is being more frequently seen in adolescents and young adults due to an increase in child obesity and inactivity. A type of diabetes called MODY is increasingly seen in adolescents, but this is classified as a diabetes due to a specific cause and not as type 2 diabetes.

Diabetes mellitus with a known etiology, such as secondary to other diseases, known gene defects, trauma or surgery, or the effects of drugs, is more appropriately called secondary diabetes mellitus or diabetes due to a specific cause. Examples include diabetes mellitus such as MODY or those caused by hemochromatosis, pancreatic insufficiencies, or certain types of medications (e.g., long-term steroid use).

Diagnosis

World Health Organization definition of diabetes is for a single raised glucose reading with symptoms, otherwise raised values on two occasions, of either:

• fasting plasma glucose ≥ 7.0 mmol/l (126 mg/dl)

or

• With a glucose tolerance test, two hours after the oral dose a plasma glucose ≥ 11.1 mmol/l (200 mg/dl)

Screening and prevention

Prevention

The recent increase in the research data on the screening and prevention is due to the fact that the benefits of prevention far outweighs that of post detection treatment. Although the U.S. Preventive Services Task Force concluded that “the evidence is insufficient to recommend for or against routinely screening asymptomatic adults for type 2 diabetes, impaired glucose tolerance, or impaired fasting glucose,” this was a grade I recommendation when published in 2003. However, the USPSTF does recommend screening for diabetics in adults with hypertension or hyperlipidemia (grade B recommendation).

In 2005, an evidence report by the Agency for Healthcare Research and Quality concluded that “there is evidence that combined diet and exercise, as well as drug therapy (metformin, acarbose), may be effective at preventing progression to DM in IGT subjects”.

Milk has also been associated with the prevention of diabetes. A questionnaire study was done by Choi et al. of 41,254 men which including a 12 year follow up showed this association. In this study, it was found that diets high in low-fat dairy might lower the risk of type 2 diabetes in men. Even though these benefits are being considered linked to milk consumption, the effect of diet is only one factor that is affecting the body’s overall health.

Accuracy of tests for early detection

If a 2-hour postload glucose level of at least 11.1 mmol/L (≥ 200 mg/dL) is used as the reference standard, the fasting plasma glucose > 7.0 mmol/L (126 mg/dL) diagnoses current diabetes with:

• sensitivity about 50%
• specificity greater than 95%

A random capillary blood glucose > 6.7 mmol/L (120 mg/dL) diagnoses current diabetes with

• sensitivity = 75%
• specificity = 88%

Glycosylated hemoglobin values that are elevated (over 5%), but not in the diabetic range (not over 7.0%) are predictive of subsequent clinical diabetes in US female health professionals. In this study, 177 of 1061 patients with glycosylated hemoglobin value less than 6% became diabetic within 5 years compared to 282 of 26281 patients with a glycosylated hemoglobin value of 6.0% or more. This equates to a glycosylated hemoglobin value of 6.0% or more having:

• sensitivity = 16.7%
• specificity = 98.9%

Benefit of early detection

Since publication of the USPSTF statement, a randomized controlled trial of prescribing acarbose to patients with “high-risk population of men and women between the ages of 40 and 70 years with a body mass index (BMI), calculated as weight in kilograms divided by the square of height in meters, between 25 and 40. They were eligible for the study if they had IGT according to the World Health Organization criteria, plus impaired fasting glucose (a fasting plasma glucose concentration of between 100 and 140 mg/dL or 5.5 and 7.8 mmol/L) found a number needed to treat of 44 (over 3.3 years) to prevent a major cardiovascular event.

Other studies have shown that lifestyle changes, xenicaland metformin can delay the onset of diabetes.

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