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Type 2 diabetes

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Type 2 diabetes
SpecialtyFamily medicine, endocrinology Edit this on Wikidata
See diabetes mellitus for further general information on diabetes.

Diabetes mellitus type 2 (formerly called diabetes mellitus type II, non insulin-dependent diabetes (NIDDM), obesity related diabetes, or adult-onset diabetes) is a metabolic disorder that is primarily characterized by insulin resistance, relative insulin deficiency, and hyperglycemia. It is often managed by engaging in exercise and modifying one's diet. It is rapidly increasing in the developed world, and there is some evidence that this pattern will be followed in much of the rest of the world in coming years. The CDC has characterized the increase as an epidemic.[1]

Unlike Type 1 diabetes, there is little tendency toward ketoacidosis in Type 2 diabetes, though it is not unknown. One effect that can occur is nonketonic hyperglycemia. Complex and multifactorial metabolic changes 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.

Pathophysiology

Insulin resistance means that body cells do not respond appropriately when insulin is present.

Other important contributing factors:

  • increased hepatic glucose production (e.g., from glycogen degradation), especially at inappropriate times
  • 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
  • Cancer survivors who received allogenic Hematopoeitic Cell Transplantation (HCT) are 3.65 times more likely to report type 2 diabetes than their siblings. Total body irradiation (TBI) is also associated with a higher risk of developing diabetes.

This is a more complex problem than type 1, but is sometimes easier to treat, especially in the initial years when insulin is often still being produced internally. Type 2 may go unnoticed for years in a patient before diagnosis, since the symptoms are typically milder (no ketoacidosis) and can be sporadic. However, severe complications can result from unnoticed type 2 diabetes, including renal failure, blindness, wounds that fail to heal, and coronary artery disease. The onset of the disease is most common in middle age and later life.

Diabetes mellitus type 2 is presently of unknown etiology (i.e., origin). 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. Examples include diabetes mellitus caused by hemochromatosis, pancreatic insufficiency, or certain types of medications (e.g. long-term steroid use). Can lead to Down Syndrome

About 90–95% of all North American cases of diabetes are type 2[2], and about 20% of the population over the age of 65 has diabetes mellitus type 2. The fraction of type 2 diabetics in other parts of the world varies substantially, almost certainly for environmental and lifestyle reasons, though these are not known in detail. Diabetes affects over 150 million people worldwide with this number expected to double by 2025[2]. There is also a strong inheritable genetic connection in type 2 diabetes: having relatives (especially first degree) with type 2 is a considerable risk factor for developing type 2 diabetes. In addition there is also a mutation to the Islet Amyloid Polypeptide gene that results in a earlier onset, more severe form of diabetes[3],[4]. About 55 percent of type 2 are obese[5] —chronic obesity leads to increased insulin resistance that can develop into diabetes, most likely because adipose tissue is a (recently identified) source of chemical signals (hormones and cytokines). Other research shows that type 2 diabetes causes obesity.[6]

Diabetes mellitus type 2 is often associated with obesity and hypertension and elevated cholesterol (combined hyperlipidemia), and with the condition Metabolic syndrome (also known as Syndrome X, Reavan's syndrome, or CHAOS). It is also associated with acromegaly, Cushing's syndrome and a number of otherendocrinological disorders. Additional factors found to increase risk of type 2 diabetes include aging[7], high-fat diets[8] and a less active lifestyle[9].

Diagnosis

The World Health Organization definition of diabetes is for a single raised glucose reading with symptoms, otherwise raised values on two occasions,of either[10]:

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

Screening and prevention

Interest has arisen in preventing diabetes due to research on the benefits of treating patients before overt diabetes. Although the U.S. Preventive Services Task Force (USPSTF) 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"[11][12], 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".[13]

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[12]:

A random capillary blood glucose > 6.7 mmol/L (120 mg/dL) diagnoses current diabetes with[14]:

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.[15] 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:

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[16].

Other studies have shown that life-style changes[17] and metformin[18] can delay the onset of diabetes.

Treatment

Diabetes mellitus type 2 is a chronic, progressive disease that has no medically proven cure. There are two main goals of treatment of the disease:

  1. reduction of mortality and concomitant morbidity (from assorted diabetic complications)
  2. preservation of quality of life

The first goal can be achieved through close glycemic control (i.e., blood glucose levels); the reduction effect in diabetic complications has been well demonstrated in several extensive clinical trials and is thus well established. The second goal is often addressed (in developed countries) by support and care from teams of diabetic health workers (physician, PA, nurse, dietitian or a certified diabetic educator). Endocrinologists, family practitioners, and general internists are the types of physicians most likely to treat people with diabetes. Knowledgeable patient participation is vital and so patient education is a crucial aspect of this effort.

Type 2 is initially treated by adjustment in diet and exercise, and by weight loss, especially in obese patients. The amount of weight loss which improves the clinical picture is sometimes modest (5–10 lb); this is almost certainly due to currently poorly understood aspects of fat tissue chemical signalling (especially in visceral fat tissue in and around abdominal organs). In many cases, such initial efforts can substantially restore insulin sensitivity.

Dietary management

Modifying the diet is known to help control glucose intake, and in response, blood glucose levels.

One 2007 study will report that in a Paleolithic diet, all 14 patients returned blood glucose levels to normal after the trial period of 12 weeks, and improved glucose tolerance (26% less blood glucose rise following a carbohydrate intake compared to 7% reduction for control group on a Mediterranean diet). This was the first Paleolithic diet study, and suggested that "it may be more efficient to avoid some of our modern foods than to count calories or carbohydrate".[19]

Other evidence for modified diets treating and being beneficial include:

Self monitoring of blood glucose

It is unclear if self-monitoring of blood glucose improves outcomes.[24]

Antidiabetic drugs

Metformin 500mg tablets
Main article: antidiabetic drugs

The most important drug now used in Type 2 Diabetes is the Biguanide metformin which works primarily by reducing liver release of blood glucose from glycogen stores as well as some increase in uptake of glucose by the body's tissues. Both historically and currently commonly used are the Sulfonylurea group, of which several members (including glibenclamide and gliclazide) are widely used; these increase glucose stimulated insulin secretion by the pancreas.

Newer drug classes include:

Selecting an antidiabetic drug

Oral drugs

A systematic review of randomized controlled trials found that metformin and second-generation sulfonylureas are the preferred choices for most[25] Failure of respose after a time is not unknown with most of these agents: the initial choice of anti-diabetic drug has been compared in a randomized controlled trial which found "cumulative incidence of monotherapy failure at 5 years of 15% with rosiglitazone, 21% with metformin, and 34% with glyburide"[26]. Of these, rosiglitazone had more weight gain and edema.[26] Rosiglitazone may increase risk of death from cardiovascular causes.[27] Pioglitazone[28] and rosiglitazone may increase the risk of fractures.[29]

Insulin preparations

If antidiabetic drugs fail (or stop helping), insulin therapy may be necessary -- usually in addition to oral medication therapy -- to maintain normal glucose levels.

The initial insulin regimen can be chosen based on the patient's blood glucose profile.[30] Initially, adding nightly insulin to patients failing oral medications may be best.[31]

When nightly insulin is insufficient, insulin can be premixed with a fixed ratio of short and intermediate acting insulin; this may be better than using long acting insulin.[32][33]. A guide to titrating fixed ratio insulin is available(http://www.annals.org/cgi/content/full/145/2/125/T4).[30]

Long acting insulins

A meta-analysis of randomized controlled trials by the Cochrane Collaboration found "only a minor clinical benefit of treatment with long-acting insulin analogues for patients with diabetes mellitus type 2".[34]

Alternative Medicines

Carnitine has been shown to increase insulin sensitivity and glucose storage in humans. [35]. It is important to note that this was with a constant blood infusion, not an oral dose, and that the clinical significance of this result is unclear.

Taurine has also shown significant improvement in insulin sensitivity and hyperlipidemia in rats.[36]

Neither of these have shown permanent positive effects, nor a complete restoration to pre-diabetes conditions, only improvement. Their clinical importance in humans remains unclear.

Antihypertensive agents

Main article: Antihypertensive

The goal blood pressure is 130/80 which is lower than in non-diabetic patients.[37]

ACE inhibitors

The HOPE study suggests that diabetics should be treated with ACE inhibitors (specifically ramipril 10 mg/d) if they have one of the following [38]:

After treatment with ramipril for 5 years the number needed to treat was 50 patients to prevent one cardiovascular death. Other ACE inhibitors may not be as effective.[39]

Hypolipidemic agents

Main article: Hypercholesterolemia § Diabetic_patients

References

  1. ^ Diabetes - Disabling Disease to Double by 2050
  2. ^ a b Zimmet, P., Alberti, K. G. M. M., Shaw, J. Global and societal implications of the diabetes epidemic. Nature 2001, 414, 782-787.
  3. ^ Sakagashira, S., Sanke, T., Hanabusa, T., Shimomura, H., Ohagi, S., Kumagaye, K. Y.,Nakajima, K. & Nanjo, K. Missense mutation of amylin gene (S20G) in Japanese NIDDM patients. Diabetes 1996, 45, 1279-1281.
  4. ^ Seino, S. S20G mutation of the amylin gene is associated with Type II diabetes in Japanese. Diabetologia 2001, 44, (7), 906-909.
  5. ^ Eberhart, M. S. (November 19, 2004). "Prevalence of Overweight and Obesity Among Adults with Diagnosed Diabetes --- United States, 1988--1994 and 1999--2002". Morbidity and Mortality Weekly Report. 53 (45). Centers for Disease Control and Prevention: 1066–1068. Retrieved 2007-03-11. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: extra punctuation (link)
  6. ^ Camastra S, Bonora E, Del Prato S, Rett K, Weck M, Ferrannini E (1999). "Effect of obesity and insulin resistance on resting and glucose-induced thermogenesis in man. EGIR (European Group for the Study of Insulin Resistance)". Int J Obes Relat Metab Disord. 23 (12): 1307–13. PMID 10643689.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Jack, L., Jr., Boseman, L. & Vinicor, F. Aging Americans and diabetes. A public health and clinical response. Geriatrics 2004, 59, 14-17.
  8. ^ Lovejoy, J. C. The influence of dietary fat on insulin resistance. Curr Diab Rep 2002, 2,435-440.
  9. ^ Hu, F. B. Sedentary lifestyle and risk of obesity and type 2 diabetes. Lipids 2003, 38,103-108.
  10. ^ .World Health Organization. "Definition, diagnosis and classification of diabetes mellitus and its complications: Report of a WHO Consultation. Part 1. Diagnosis and classification of diabetes mellitus". Retrieved 2007-05-29.
  11. ^ U.S. Preventive Services Task Force (2003). "Screening for type 2 diabetes mellitus in adults: recommendations and rationale". Ann. Intern. Med. 138 (3): 212–4. PMID 12558361. National Guidelines Clearinghouse: Complete Summary
  12. ^ a b Harris R, Donahue K, Rathore SS, Frame P, Woolf SH, Lohr KN (2003). "Screening adults for type 2 diabetes: a review of the evidence for the U.S. Preventive Services Task Force". Ann. Intern. Med. 138 (3): 215–29. PMID 12558362.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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  14. ^ Rolka DB, Narayan KM, Thompson TJ; et al. (2001). "Performance of recommended screening tests for undiagnosed diabetes and dysglycemia". Diabetes Care. 24 (11): 1899–903. PMID 11679454. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  15. ^ Pradhan AD, Rifai N, Buring JE, Ridker PM (2007). "Hemoglobin A1c predicts diabetes but not cardiovascular disease in nondiabetic women". Am. J. Med. 120 (8): 720–7. doi:10.1016/j.amjmed.2007.03.022. PMID 17679132.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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  19. ^ "Original Human 'Stone Age' Diet Is Good For People With Diabetes, Study Finds". ScienceDaily.com. June 28, 2007. Retrieved 2007-07-24.
  20. ^ Nicholson A (02/15/05). "Diabetes: Can a Vegan Diet Reverse Diabetes?". Physicians Committee for Responsible Medicine. Retrieved 2007-07-24. {{cite web}}: Check date values in: |date= (help)
  21. ^ Barnard ND, Cohen J, Jenkins DJ; et al. (2006). "A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes". Diabetes Care. 29 (8): 1777–83. doi:10.2337/dc06-0606. PMID 16873779. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
    Related news articles:
  22. ^ Nielsen JV, Joensson E (2006). "Low-carbohydrate diet in type 2 diabetes. Stable improvement of bodyweight and glycemic control during 22 months follow-up". Nutrition & metabolism. 3: 22. doi:10.1186/1743-7075-3-22. PMID 16774674.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  23. ^ Khan A, Bryden NA, Polansky MM, Anderson RA (1990). "Insulin potentiating factor and chromium content of selected foods and spices". Biological trace element research. 24 (3): 183–8. PMID 1702671.{{cite journal}}: CS1 maint: multiple names: authors list (link)
    Related news articles:
  24. ^ Farmer A, Wade A, Goyder E; et al. (2007). "Impact of self monitoring of blood glucose in the management of patients with non-insulin treated diabetes: open parallel group randomised trial". doi:10.1136/bmj.39247.447431.BE. PMID 17591623. {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
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  26. ^ a b Kahn SE, Haffner SM, Heise MA; et al. (2006). "Glycemic durability of rosiglitazone, metformin, or glyburide monotherapy". N. Engl. J. Med. 355 (23): 2427–43. doi:10.1056/NEJMoa066224. PMID 17145742. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  27. ^ "NEJM -- Effect of Rosiglitazone on the Risk of Myocardial Infarction and Death from Cardiovascular Causes". Retrieved 2007-05-21.
  28. ^ "MedWatch - 2007 Safety Information Alerts". Retrieved 2007-05-21.
  29. ^ "MedWatch - 2007 Safety Information Alerts". Retrieved 2007-05-21.
  30. ^ a b Mooradian AD, Bernbaum M, Albert SG (2006). "Narrative review: a rational approach to starting insulin therapy". Ann. Intern. Med. 145 (2): 125–34. PMID 16847295.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  31. ^ Yki-Järvinen H, Kauppila M, Kujansuu E; et al. (1992). "Comparison of insulin regimens in patients with non-insulin-dependent diabetes mellitus". N. Engl. J. Med. 327 (20): 1426–33. PMID 1406860. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  32. ^ Raskin P, Allen E, Hollander P; et al. (2005). "Initiating insulin therapy in type 2 Diabetes: a comparison of biphasic and basal insulin analogs". Diabetes Care. 28 (2): 260–5. PMID 15677776. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  33. ^ Malone JK, Kerr LF, Campaigne BN, Sachson RA, Holcombe JH (2004). "Combined therapy with insulin lispro Mix 75/25 plus metformin or insulin glargine plus metformin: a 16-week, randomized, open-label, crossover study in patients with type 2 diabetes beginning insulin therapy". Clinical therapeutics. 26 (12): 2034–44. doi:10.1016/j.clinthera.2004.12.015. PMID 15823767.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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  35. ^ Geltrude Mingrone, Aldo V. Greco, Esmeralda Capristo, Giuseppe Benedetti, Annalisa Giancaterini, Andrea De Gaetano, and Giovanni Gasbarrini (1999). "L-Carnitine Improves Glucose Disposal in Type 2 Diabetic Patients". Journal of the American College of Nutrition. 18 (1): 77–82.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  36. ^ "Taurine improves insulin sensitivity in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous type 2 diabetes". American Journal of Clinical Nutrition. 71 (1): 54–58. {{cite journal}}: Text "date January 2000" ignored (help)
  37. ^ Chobanian AV, Bakris GL, Black HR; et al. (2003). "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report". JAMA. 289 (19): 2560–72. doi:10.1001/jama.289.19.2560. PMID 12748199. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  38. ^ Yusuf S, Sleight P, Pogue J, Bosch J, Davies R, Dagenais G (2000). "Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients. The Heart Outcomes Prevention Evaluation Study Investigators". N. Engl. J. Med. 342 (3): 145–53. PMID 10639539.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  39. ^ Pilote L, Abrahamowicz M, Rodrigues E, Eisenberg MJ, Rahme E (2004). "Mortality rates in elderly patients who take different angiotensin-converting enzyme inhibitors after acute myocardial infarction: a class effect?". Ann. Intern. Med. 141 (2): 102–12. PMID 15262665.{{cite journal}}: CS1 maint: multiple names: authors list (link)

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