Control of Blood Sugar

Diabetes Mellitus

Maintaining Glucose Homeostasis

• Goal is to maintain blood sugar levels between ~ 70 and 110 mg/dL

• Two hormones play a role in maintaining glucose homeostasis:– Insulin– Glucagon

• Both are pancreatic hormones

Lowering Blood Glucose Levels

• Blood glucose levels rise due to eating a carbohydrate containing meal

– In response, the pancreas releases insulin into the blood.• Beta cells of the pancreas release insulin

Lowering Blood Glucose Levels

• Insulin– Binds to insulin receptors on cells.

– Cells allow glucose to enter

– Stimulates liver and muscle cells to store glucose as glycogen

– Stimulates excess glucose to be converted into fat.

– As a result, blood glucose levels drop.

Raising Blood Glucose Levels

• Blood glucose levels drop as cells use glucose.– In response, the pancreas releases glucagon

into the blood.• Alpha cells of the pancreas release glucagon

Raising Blood Glucose Levels

• Glucagon:– Stimulates liver cells to break down glycogen

and release the glucose into the blood.

• As a result blood glucose levels rise.

Diabetes Mellitus

• Diabetes mellitus refers to a group of metabolic disorders in which the body is unable to regulate high blood glucose levels.

Diabetes Mellitus

• Two common forms:– Type 1 diabetes

• Other names: – “Juvenile” diabetes– Insulin dependent diabetes mellitus (IDDM)

– Type 2 diabetes• Other names:

– “Adult onset” diabetes– Noninsulin dependent diabetes mellitus (NIDDM)

Incidence of Diabetes

• Type 1 Diabetes– 5-10 % of diabetics– Onset is generally before age 20

• Average age of onset ~12

• Type 2 Diabetes– 90-95% of diabetics– Onset is generally between ages 10-19 or

after age 40

Type 1 Diabetes

• Possible causes:– Autoimmune disorder

• Genetic component• Immune system destroys beta cells of pancreas

– May also be caused by a viral infection that damages the pancreas

Type 1 Diabetes

• Pancreas is unable to make/secrete insulin.– Glucose cannot enter cells hunger– Blood glucose levels rise

• Glucose “spills” into the urine• Water moves into blood

– Frequent need to urinate– Thirsty

Type 1 Diabetes

– Cells use fats and proteins as an energy source, results in:

• Weight loss hunger• Ketones produced (due to “overuse” of fats for

energy) potential for diabetic acidosis

Type 1 Diabetes

– Diabetic acidosis (ketosis)• Ketones in breath• Ketones in blood and urine

can lead to diabetic coma

Type 1 Diabetes

• Treatment– Insulin shots or pump– Highly regulate intake of carbohydrates

• Consistent pattern of moderate carbohydrate intake to minimize fluctuations in blood glucose

– Closely monitor blood glucose levels

Type 2 Diabetes

• Associated with obesity– As gain weight, cells make fewer insulin

receptors– Insulin doesn’t bind as well to receptors made

• Genetic component

• More common as age

Type 2 Diabetes

• Fewer insulin receptors on cells

• Less insulin binds to cells– Glucose enters cells SLOWLY

• Blood glucose levels remain elevated• Glucose “spills” into the urine• Water moves into blood

– Frequent need to urinate– Thirsty

Type 2 Diabetes

• Glucose enters cells slowly…– No need to use proteins or fats for energy– Hungry– Eat more gain weight

• Exacerbates the problem

Type 2 Diabetes

– Pancreas continues to make insulin• Often in large amounts to compensate for the

insulin resistance of cells• May get to point where pancreas cannot keep up

with the body’s needs and insulin is required.

© 2008 Thomson - Wadsworth

Type 2 Diabetes

• Recommendations– Lose weight

• Even moderate weight loss can help

– Exercise• Increases number of insulin receptors• Improves binding of insulin to the receptors• Helps with weight loss

Chronic Complications of Diabetes

• Regular high blood glucose levels result in – Cells making sugar alcohols– Glucose binds to proteins on cells, damages

cells

• Results in:– Damage to blood vessels and nerves

– Slowed healing– Unaware of wounds…… amputation– Kidney damage kidney failure– Damage to cells of eyes blindness

Chronic Complications of Diabetes

• Other:– Increased risk of:

• Coronary heart disease• Elevated blood lipid levels• Hypertension

– Adults with diabetes have heart disease and stroke death rates ~ 2 to 4 times higher than adults without diabetes.

2007 US Data

• Total: 7.8% of the population has diabetes– Age 60 or older 23.1% have diabetes– 1 in 6 overweight adolescents aged 12-19

have pre-diabetes

• More Statistics

% of people 65 or older with diabetes by race in the U.S.

0%

5%

10%

15%

20%

25%

30%

35%

1988-1994 2001-2004

White

Black

MexicanAmerican

Source: CDC/NCHS