Transcript Control of Blood Sugar

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.
35%
30%
25%
White
20%
Black
15%
Mexican
American
10%
5%
0%
1988-1994
2001-2004
Source: CDC/NCHS