Diabetes is a disorder of metabolism the way our bodies use digested food for growth and energy. Most of the food we eat is broken down into glucose, the form of sugar in the blood. Glucose is the main source of fuel for the body. For glucose to get into cells, insulin must be present.
When we eat, the pancreas automatically produces the right amount of insulin to move glucose from blood into our cells. In people with diabetes, however, the pancreas either produces little or no insulin, or the cells do not respond appropriately to the insulin that is produced. Glucose builds up in the blood, overflows into the urine, and passes out of the body in the urine.

Types of Diabetes

There are 4 main types:

1 - Type 1 Diabetes
In Type 1 Diabetes, the pancreas produces little or no insulin.
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A person who has type 1 diabetes must take insulin daily to live. It develops most often in children and young adults but can appear at any age.



2 - Type 2 Diabetes
When type 2 diabetes is diagnosed, the pancreas is usually producing enough insulin, but for unknown reasons the body cannot use the insulin effectively, a condition called insulin resistance. After several years, insulin production decreases.
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The most common form of diabetes is type 2 diabetes. About 90 to 95 percent of people with diabetes have type 2. This form of diabetes is most often associated with older age, obesity, family history of diabetes, previous history of gestational diabetes, physical inactivity, and certain ethnicities. About 80 percent of people with type 2 diabetes are overweight. Type 2 diabetes is increasingly being diagnosed in children and adolescents.



3 - Gestational Diabetes
Gestational diabetes is caused by the hormones of pregnancy or a shortage of insulin.
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Some women develop gestational diabetes late in pregnancy. Although this form of diabetes usually disappears after the birth of the baby, women who have had gestational diabetes have a 20 to 50 percent chance of developing type 2 diabetes within 5 to 10 years. As with type 2 diabetes, gestational diabetes occurs more often in some ethnic groups and among women with a family history of diabetes.

4 - Pre-diabetes
In pre-diabetes, blood glucose levels are higher than normal but not high enough to be characterized as diabetes.
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However, many people with pre-diabetes develop type 2 diabetes within 10 years. Pre-diabetes also increases the risk of heart disease and stroke. With modest weight loss and moderate physical activity, people with pre-diabetes can delay or prevent type 2 diabetes.


Source: Diabetes Overview (diabetes.niddk.nih.gov)

Causes

Type 1 Diabetes
Type 1 diabetes is believed to be an autoimmune disease. The body's immune system attacks the cells in the pancreas that produce insulin.
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Risk factors for type 1 diabetes include the following: A predisposition to develop type 1 diabetes may run in families but much less so than for type 2. Environmental factors, such as certain types of viral infections, may also contribute. Type 1 diabetes is most common in people of non-Hispanic white persons of Northern European descent, followed by African Americans and Hispanic Americans. It is relatively rare in those of Asian descent. Type 1 diabetes is slightly more common in men than in women.

Type 2 diabetes
Type 2 diabetes is believed to have a strong genetic link, meaning that it tends to run in families.
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Risk factors for type 2 diabetes include the following: High blood pressure High blood triglyceride (fat) levels Gestational diabetes or giving birth to a baby weighing more than 9 pounds High-fat diet High alcohol intake Sedentary lifestyle Obesity or being overweight Ethnicity: Certain groups, such as African Americans, Native Americans, Hispanic Americans, and Japanese Americans, have a greater risk of developing type 2 diabetes than non-Hispanic whites. Aging: Increasing age is a significant risk factor for type 2 diabetes. Risk begins to rise significantly at about age 45 years, and rises considerably after age 65 years.


Source: Diabetes Risks, Symptoms, Causes, Diagnosis, and Treatment Information on eMedicineHealth.com (emedicinehealth.com)

Epidemiology

The worldwide prevalence of Diabetes was 171,000,000 in the year 2000 and has been estimated to reach 366,000,000 by year 2030.
Source: (who.int)

Prevention

Maintaining an ideal body weight and an active lifestyle may prevent the onset of type 2 diabetes. Currently there is no way to prevent type 1 diabetes.
Source: MedlinePlus Medical Encyclopedia: Diabetes (nlm.nih.gov)

Symptoms

Type 1 Diabetes:
The symptoms often begin abruptly and dramatically.
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A condition called diabetic ketoacidosis may quickly develop. Without insulin, most cells cannot use the sugar that is in the blood. The initial symptoms of diabetic ketoacidosis include excessive thirst and urination, weight loss, nausea, vomiting, fatigue, and particularly in children, abdominal pain. Breathing tends to become deep and rapid as the body attempts to correct the blood's acidity. The person's breath smells like nail polish remover, the smell of the ketones escaping into the breath. Without treatment, diabetic ketoacidosis can progress to coma and death, sometimes within a few hours.

Type 2 Diabetes:
People with type 2 diabetes may not have any symptoms for years or decades before they are diagnosed. Symptoms may be subtle.
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Increased urination and thirst are mild at first and gradually worsen over weeks or months. Eventually, the person feels extremely fatigued, is likely to develop blurred vision, and may become dehydrated. Because people with type 2 diabetes produce some insulin, ketoacidosis does not usually develop. However, the blood sugar levels can become extremely high (often exceeding 1,000 mg/dL). When the blood sugar levels get very high, the person may develop severe dehydration, which may lead to mental confusion, drowsiness, and seizures, a condition called nonketotic hyperglycemic-hyperosmolar coma.


Source: Diabetes Mellitus (DM): Hormonal Disorders: Merck Manual Home Edition (merck.com)

Complications of Diabetes
Diabetic complications can be classified broadly as microvascular (complications arising from small vessel damage) or macrovascular disease (complications arising from large vessel damage).
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Microvascular complications include neuropathy (nerve damage), nephropathy (kidney disease) and vision disorders (eg retinopathy, glaucoma, cataract and corneal disease). Macrovascular complications include heart disease, stroke and peripheral vascular disease (which can lead to ulcers, gangrene and amputation). Other complications of diabetes include infections, metabolic difficulties, impotence, autonomic neuropathy and pregnancy problems.


Source: Complications of Diabetes (healthinsite.gov.au)

Diagnosis

The following tests are used for diagnosis:

Fasting Plasma Glucose (FPG) Test
A fasting plasma glucose test measures your blood glucose after you have gone at least 8 hours without eating. This test is used to detect diabetes or pre-diabetes.
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Table 1. Fasting Plasma Glucose Test Plasma Glucose Result(mg/dL) Diagnosis 99 and below Normal 100 to 125 Pre-diabetes(impaired fasting glucose) 126 and above Diabetes* *Confirmed by repeating the test on a different day.

Oral Glucose Tolerance Test (OGTT)
An oral glucose tolerance test measures your blood glucose after you have gone at least 8 hours without eating and 2 hours after you drink a glucose-containing beverage. This test can be used to diagnose diabetes or pre-diabetes.
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The OGTT requires you to fast for at least 8 hours before the test. Your plasma glucose is measured immediately before and 2 hours after you drink a liquid containing 75 grams of glucose dissolved in water. Table 2. Oral Glucose Tolerance Test 2-Hour Plasma Glucose Result (mg/dL) Diagnosis 139 and below Normal 140 to 199 Pre-diabetes (impaired glucose tolerance) 200 and above Diabetes* *Confirmed by repeating the test on a different day.

Gestational diabetes is also diagnosed based on plasma glucose values measured during the OGTT.
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Blood glucose levels are checked four times during the test. If your blood glucose levels are above normal at least twice during the test, you have gestational diabetes.

Random Plasma Glucose Test
In a random plasma glucose test, your doctor checks your blood glucose without regard to when you ate your last meal.
This test, along with an assessment of symptoms, is used to diagnose diabetes but not pre-diabetes.
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A random blood glucose level of 200 mg/dL or more, plus presence of the following symptoms, can mean that you have diabetes: increased urination increased thirst unexplained weight loss Other symptoms include fatigue, blurred vision, increased hunger, and sores that do not heal.


Source: Diagnosis of Diabetes (diabetes.niddk.nih.gov)

Treatment

People with type 1 diabetes who are able to maintain a healthy weight may be able to avoid the need for large doses of insulin.
People with type 2 diabetes may be able to avoid the need for all drugs by achieving and maintaining a healthy weight.
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In general, people with diabetes should not eat much sweet food. They should also try to eat meals on a regular schedule; long periods between eating should be avoided. People with diabetes also tend to have high levels of cholesterol in the blood, so limiting the amount of saturated fat in the diet is important. Appropriate amounts of exercise can also help people control their weight and maintain blood sugar levels within the normal range.

Insulin Replacement Therapy
People with type 1 diabetes almost always require insulin therapy, and many people with type 2 diabetes require it as well.
Insulin is usually injected; it currently cannot be taken by mouth because insulin is destroyed in the stomach.
Source: Diabetes Mellitus (DM): Hormonal Disorders: Merck Manual Home Edition (merck.com)

Oral Antihyperglycemic drugs
Unlike type 1 diabetes, type 2 diabetes may respond to treatment with exercise, diet, and medicines taken by mouth.
There are several types of medicines used to lower blood glucose in type 2 diabetes.
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They fall into one of three groups: 1. Medications called oral sulfonylureas that increase insulin production by the pancreas. 2. Medications called thiazolidinediones that help increase the cell's sensitivity (responsiveness) to insulin. 3. Medications that delay absorption of glucose from the gut. These include acarbose and miglitol. There are some injectable medicines used to lower blood sugar. Most persons with type 2 diabetes will need more than one medication for good blood sugar control within 3 years of starting their first medication.

Gestational diabetes is treated with insulin and changes in diet.
Source: MedlinePlus Medical Encyclopedia: Diabetes (nlm.nih.gov)

Illustrations

News

Racial difference in A1C may be biologic variation
Source: MedlinePlus: Racial difference in A1C may be biologic variation (nlm.nih.gov)

Silent heart disease common in diabetics
Source: MedlinePlus: Silent heart disease common in diabetics (nlm.nih.gov)

Health Tip: Diabetics, Examine Your Feet Good foot care can prevent problems
Source: HealthDay (healthday.com)

Control of diabetes may prevent infertility
Source: MedlinePlus: Control of diabetes may prevent infertility (nlm.nih.gov)

Scientific Articles (a selection for health professionals)

Early infant feeding and risk of type 1 diabetes mellitus-a nationwide population-based case-control study in pre-school children.
Rosenbauer J, Herzig P, Giani G.
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BACKGROUND The evidence on the role of environmental factors in the development of type 1 diabetes is conflicting. Reducing potential bias and the variety of exposures, we investigated the association between type 1 diabetes risk and nutritional and environmental exposures in pre-school children. METHODS This nationwide population-based case-control study included 760 cases under 5 years of age newly diagnosed with type 1 diabetes during 1992-1995. From the general population, 1871 controls were randomly selected and individually matched on age ( +/- 1 year), sex, and residence. Information on infant diet, foetal, perinatal and socio-economic factors, and familial diabetes was obtained by a parent-administered questionnaire. Data were analysed by multiple conditional logistic regression. RESULTS Duration of breastfeeding and age at introduction of bottle-feeding were inversely associated with type 1 diabetes risk according to a dose-response relationship (trend test p < 0.05). Adjusted odd ratios (95% CI) for a long breastfeeding period and a late introduction of bottle-feeding (>/=5 month versus < 2 weeks) were 0.71 (0.54-0.93) and 0.80 (0.62-1.04), respectively. Familial type 1 diabetes, maternal age > 40 years, and low birth weight were found more frequently among diabetic than among control children. Current cow's milk consumption, higher social status, and a larger family were associated with a reduced diabetes risk. Up to one half of the diabetic cases in the population could be attributed to modifiable exposures. CONCLUSIONS Our findings indicate that infant feeding is associated with type 1 diabetes risk and that a considerable part of new type 1 diabetic cases is potentially preventable. Full reference of the article: Rosenbauer J, Herzig P, Giani G. Institute of Biometrics and Epidemiology, German Diabetes Centre, Leibniz Institute at Heinrich-Heine University Dsseldorf, Germany. "Early infant feeding and risk of type 1 diabetes mellitus-a nationwide population-based case-control study in pre-school children." Diabetes/metabolism research and reviews, October 2007


Source: PubMed (ncbi.nlm.nih.gov)

Aldose reductase inhibitors for the treatment of diabetic polyneuropathy
Chalk C, Benstead TJ, Moore F
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Summary Polyneuropathy is a common complication of diabetes mellitus that causes pain and sensory and motor deficits in the arms and legs. It can also lead to foot ulcers and amputation. Aldose reductase inhibitors are a class of medications that block the breakdown of glucose by a specific metabolic pathway called the polyol pathway, and may potentially slow or reverse progression of neuropathy. The authors reviewed the results of all randomized trials that compared an aldose reductase inhibitor with a control and lasted at least six months. Many of the 32 randomized controlled trials identified had significant methodological flaws. The trials used a variety of measures to look for a benefit of treatment with aldose reductase inhibitors. The authors elected to focus primarily on changes in muscle strength and sensation. These were chosen because they are thought be the best indicator of the severity of polyneuropathy, and they have been used in a previous landmark study of the effects of intensive blood sugar control on diabetic neuropathy, as well as in studies of treatments in other types of polyneuropathy. Muscle strength or sensation were assessed in 29 trials, but sufficient data for analysis was only available in 13 studies, involving 879 treated participants and 906 controls. There was no overall significant difference between the treated and control groups. For one drug, tolrestat, there was possibly some benefit, but concerns about liver toxicity have lead to withdrawal of tolrestat from use in humans. A few trials did report that symptoms of neuropathy improved for the treated group, but this was contradicted by most other trials. No benefit was detected on electromyography (EMG) parameters (27 studies) or foot ulceration (one study). Quality of life was not assessed in any of the studies. Adverse effects were infrequent and were mostly minor, except for severe allergic reactions with sorbinil, impaired kidney function with zenarestat, and alteration of liver function with tolrestat. The authors concluded that there was no significant benefit of treatment with aldose reductase inhibitors for diabetic polyneuropathy. Abstract Background Polyneuropathy, a common complication of diabetes mellitus, causes pain and sensory and motor deficits in the limbs, and is also an important independent predictor of foot ulceration. Inhibiting the metabolism of glucose by the polyol pathway using aldose reductase inhibitors is a potential mechanism to slow or reverse the neuropathy's progression. Objectives To assess the effects of aldose reductase inhibitors on the progression of symptoms, signs or functional disability in diabetic polyneuropathy. Search strategy We searched the Cochrane Neuromuscular Disease Group Trials Register, MEDLINE (from January 1966 to May 2007), EMBASE (from January 1980 to May 2007) and LILACS (from 1982 to May 2007). We reviewed bibliographies of randomized trials identified, and contacted authors and experts in the field. Selection criteria We included randomized controlled trials comparing an aldose reductase inhibitor with control, and lasting at least six months. The primary outcome measure was change in neurological function, measured in various ways, including strength testing, sensory examination, and composite scores of neurological examination. Secondary outcome measures were nerve conduction studies, neuropathic symptoms, quality of life, occurrence of foot ulcers and adverse effects. Data collection and analysis Trials included in the review were selected and assessed independently by at least two of us. Methodological criteria and study results were recorded on data extraction forms. Main results Thirty-two randomized controlled trials meeting the inclusion criteria were identified. Many had significant methodological flaws. Change in neurological function, our primary outcome measure, was assessed in 29 trials, but sufficient data for meta-analysis were only available in 13 studies, involving 879 treated participants and 909 controls. There was no overall significant difference between the treated and control groups (SMD -0.25, 95% CI -0.56 to 0.05), although one subgroup analysis (four trials using tolrestat) favored treatment. A benefit for neuropathic symptoms was suggested by a group of trials using a dichotomized endpoint (improvement or not), but this was contradicted by another group of trials which measured symptoms on a continuous scale. There was no overall benefit on nerve conduction parameters (27 studies) or foot ulceration (one study). Quality of life was not assessed in any of the studies. While most adverse events were infrequent and minor, three compounds had dose limiting adverse events that lead to their withdrawal from human use: severe hypersensitivity reactions with sorbinil, elevation of creatinine with zenarestat, and alteration of liver function with tolrestat. Authors' conclusions We found no statistically significant difference between aldose reductase inhibitors and placebo in the treatment of diabetic polyneuropathy. Any future clinical trials of aldose reductase inhibitors should be restricted to compounds proven to have substantial biological or preclinical advantages over previously tested agents. Full reference of the article: Chalk C, Benstead TJ, Moore F. "Aldose reductase inhibitors for the treatment of diabetic polyneuropathy" Cochrane Database of Systematic Reviews 2007, Issue 4. Art. No.: CD004572. DOI: 10.1002/14651858.CD004572.pub2


Source: The Cochrane Collaboration (cochrane.org)

Protein restriction for diabetic renal disease
Robertson L, Waugh N, Robertson
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Summary Effects of protein restriction for diabetic renal disease are unclear. Based on 12 studies, including from eight to 160 people with type 1 and type 2 diabetes for at least an average four-month period, restricted protein intake appeared to slow progression of diabetic kidney disease, but not by much on average. However, individual variation existed, therefore a low-protein diet may benefit some individuals. A low-protein diet can be difficult to adhere to, especially over the long term. Reducing the amount of animal protein is the usual method but some evidence suggests that a shift from red meat to white meat and fish or vegetables may give similar results. We found no data on the effects of low-protein diet on health-related quality of life and costs. Abstract Background Diabetic renal disease (diabetic nephropathy) is a leading cause of end-stage renal failure. Once the process has started, it cannot be reversed by glycaemic control, but progression might be slowed by control of blood pressure and protein restriction. Objectives To assess the effects of dietary protein restriction on the progression of diabetic nephropathy in patients with diabetes. Search strategy We searched The Cochrane Library, MEDLINE, EMBASE, ISI Proceedings, Science Citation Index Expanded and bibliographies of included studies. Selection criteria Randomised controlled trials (RCTs) and before and after studies of the effects of a modified or restricted protein diet on diabetic renal function in people with type 1 or type 2 diabetes following diet for at least four months were considered. Data collection and analysis Two reviewers performed data extraction and evaluation of quality independently. Pooling of results was done by means of random-effects model. Main results Twelve studies were included, nine RCTs and three before and after studies. Only one study explored all-cause mortality and end-stage renal disease (ESRD) as endpoints. The relative risk (RR) of ESRD or death was 0.23 (95% confidence interval (CI) 0.07 to 0.72) for patients assigned to a low protein diet (LPD). Pooling of the seven RCTs in patients with type 1 diabetes resulted in a non-significant reduction in the decline of glomerular filtration rate (GFR) of 0.1 ml/min/month (95% CI -0.1 to 0.3) in the LPD group. For type 2 diabetes, one trial showed a small insignificant improvement in the rate of decline of GFR in the protein-restricted group and a second found a similar decline in both the intervention and control groups. Actual protein intake in the intervention groups ranged from 0.7 to 1.1 g/kg/day. One study noted malnutrition in the LPD group. We found no data on the effects of LPDs on health-related quality of life and costs. Authors' conclusions The results show that reducing protein intake appears to slightly slow progression to renal failure but not statistically significantly so. However, questions concerning the level of protein intake and compliance remain. Further longer-term research on large representative groups of patients with both type 1 and type 2 diabetes mellitus is necessary. Because of the variability amongst patients, there might perhaps be a six month therapeutic trial of protein restriction in all individuals, with continuation only in those who responded best. Trials are required of different types of protein. Full reference of the article: Robertson L, Waugh N, Robertson A. "Protein restriction for diabetic renal disease" Cochrane Database of Systematic Reviews 2000, Issue 2. Art. No.: CD002181. DOI: 10.1002/14651858.CD002181.pub2


Source: The Cochrane Collaboration (cochrane.org)