Diabetes Mellitus Overview and Treatments

Diabetes Mellitus : a group of diseases characterized by high levels of blood glucose resulting from defects in insulin production, insulin action, or both

Consists of 3 types:1) Type 1 diabetes2) Type 2 diabetes3) Gestational diabetes

Complications :- Stroke- Heart attack- Kidney disease- Eye Disease- Nerve Damage

Diabetes Mellitus Type 1 Diabetes

- cells that produce insulin are destroyed - results in insulin dependence- commonly detected before 30

Type 2 Diabetes- blood glucose levels rise due to

1) Lack of insulin production

2) Insufficient insulin action (resistant cells)

- commonly detected after 40

- effects > 90%

- eventually leads to β-cell failure (resulting in insulin dependence)

Gestational Diabetes 3-5% of pregnant women in the US develop gestational diabetes

Testing :

Fasting Plasma Glucose Test

(FPG) - (cheap, fast)

*fasting B.G.L. 100-125 mg/dl signals pre-diabetes

*>126 mg/dl signals diabetes

Oral Glucose Tolerance Test

(OGTT)

*tested for 2 hrs after glucose-

rich drink

*140-199 mg/dl signals pre-

diabetes

*>200 mg/dl signals diabetes

80 to 90 mg per 100 ml, is the normal fasting blood glucose concentration in humans and most mammals which is associated with very low levels of insulin secretion.

A.K.A.: Glycated Hemoglobin tests A1C

Diabetes - Insulin Discovered in 1921 by Banting

and Best Consist of A & B chains linked

by 2 disulfide bonds

(plus additional disulfide in A)~ ~ ~ ~ A = 21amino acids B = 30 amino acids

Diabetes – Insulin(synthesis, storage, secretion) Produced within the pancreas by β cells islets of Langerhans insulin mRNA is translated as a single chain precursor called preproinsulin removal of signal peptide during insertion into the endoplasmic reticulum generates proinsulin Within the endoplasmic reticulum, proinsulin is exposed to several specific endopeptidases which excise the C peptide, thereby generating

the mature form of insulin

Stored as β granules

This light micrograph of a section of the human pancreas shows one of the islets of Langerhans, center, a group of modified glandular cells. These cells secrete insulin, a hormone that helps the body metabolize sugars, fats, and starches. The blue and white lines in the islets of Langerhans are blood vessels that carry the insulin to the rest of the body.

Zn

Diabetes – Insulin(Biochemical Role)

-Tyrosine Kinase receptors are the locks in which the insulin key fits- Involved in signal transduction(insulin hormone being 1st messenger)

In the case of type 1 diabetes, insulin levels are grossly deficient. Thus type 1 diabetes is invariably treated with insulin

Type 2 diabetes is frequently associated with obesity. Serum insulin levels are normal or elevated, so this is a disease of insulin resistance. A number of treatment options may be employed.

Pancreatic Hormones and Insulin Receptor Agonists

The bulk of the pancreas is an exocrine gland secreting pancreatic fluid into the duodenum after a meal.

Inside the pancreas are millions of clusters of cells called islets of Langerhans. The islets are endocrine tissue containing four types of cells. In order of abundance, they are:

beta cells, which secrete insulin and amylin; alpha cells, which secrete glucagon; delta cells, which secrete somatostatingamma cells, which secrete a polypeptide.

Pancreatic Hormones

Insulin Amylin Glucagon Somatostatin Pancreatic Polypeptide

A chain

B chain

Beta cells have channels in their plasma membrane that serve as glucose detectors. Beta cells secrete insulin in response to a rising level of circulatingglucose.

Insulin is a small protein consisting of an A chain of 21 amino acids linked by two disulfide (S—S) bridges to a B chain of 30 amino acids.

Insulin affects many organs:

It stimulates skeletal muscle fibers.

It stimulates liver cells.

It acts on fat cells

It inhibits production of certain enzyme.

In each case, insulin triggers these effects by binding to the insulin receptor.

glucoseuptake

glycogen synthesis

protein synthesis

amino acids uptake

enzymeproduction

glycogenbreaking

fat synthesis

Who need insulin medicine

Type I (insulin dependent) diabetes patients whose body produces no insulin.

Type 2 diabetes patients that do not always produce enough insulin.

Treatment

subcutaneous injection

Stage 1 Insulin was extracted from the glands of cows and pigs. (1920s)

Stage 2 Convert pig insulin into human insulin by removing the one amino acid that distinguishes them and replacing it with the human version.

Insulin drug evolution

Stage 3 Insert the human insulin gene into E. coli and culture the recombinant E.coli to produce insulin (trade name = Humulin®). Yeast is also used to produce insulin (trade name =

Novolin®) (1987).

Recombinant DNA technology has also made it possible to manufacture slightly-modified forms of human insulin that work faster (Humalog® and NovoLog®) or slower (Lantus®) than regular human insulin.

Diabetes – Oral Medications

Sulfonylureas Biguanides Sulfonylureas and biguanide combination

drugs Thiazolidinediones Alpha-glycosidase inhibitors Meglitinides

6 Classes :

Sulfonylureas : stimulate β cells to produce more insulin

1st generation– (1)Orinase (tolbutamide)– (3)Tolinase (tolazamide)– (6)Diabinese (chlorpropamide)

2nd generation– (75)Glucotrol (glipizide)– (150)Glucotrol XL (ex. rel. glipizide)– (150)Micronase, Diabeta (glyburide)– (250)Glynase (micronized glyburide)

3rd generation– (350)Amaryl (glimepiride)

2-(p-aminobenzenesulfonamido)-5-isopropyl -thiadiazole (IPTD) was used in treatment of typhoid fever in 1940’s hypoglycemia

Currently > 12,000

Re

l. P

oten

cy

bin

d to

pro

tein

may become dislodged delayed activity

*Hydroxylation of the aromatic ring appears to be the most favored metabolic pathway*Hydroxylated derivatives have much lower hypoglycemic activity

Mechanism of Action

Sulfonylureas interact with receptors on pancreatic -cells to block ATP-sensitive potassium channels

This, in turn, leads to opening of calcium channels

Which leads to the production of insulin

Biguanides : improves insulin’s ability to move glucose into cells (esp. muscle)

Metformin- Glucophage®, Fortamet®, Riomet®

*only anti-diabetic drug that has been proven to reduce the complications of diabetes, as evidenced in a large study of overweight patients with diabetes (UKPDS 1998).

- Metformin was first described in the scientific literature in 1957 (Unger et al). - It was first marketed in France in 1979 but did not receive FDA approval for Type 2 diabetes until 1994.

NN

NN

N

RR R

R

RR

R

N N

N

N

N

H

H

H

H H

+ HCl

- mechanism improves insulin sensitivity by increasing peripheral glucose uptake and utilization.

Metformin is a widely used monotherapy, and also used in combination with the sulfonylureas in treatment of type 2 diabetes

Sulfonylurea & Biguanide Combo drugs/ Cocktails

Glucovance® (Glyburide & Metformine HCl)

NH

O

NH

SO

O

O

O

NH

Cl

1-[[ p-[ 2-( 5-chloro-o-anisamido) ethyl] phenyl] sulfonyl]-3-cyclohexylurea

N N

N

N

N

H

H

H

H H

+ HCl

&

&

Thiazolidinediones (TZD’s) : make cells more sensitive to insulin (esp. fatty cells)

Pioglitazone- Actos®, Avandia®

- binds to and activates the gamma isoform of the peroxisome proliferator-activated receptor (PPARγ).

- PPARγ is a member of the steroid hormone nuclear receptor superfamily, and is found in adipose tissue, cardiac and skeletal muscle, liver and placenta

PPAR - γ

- upon activation of this nuclear receptor by a ligand such as a TZD, PPARγ–ligand complex binds to a specific region of DNA and thereby regulates the transcription of many genes involved in glucose and fatty acid metabolism.

S

NH

O

O

ON

5-{4-[2-(5-Ethyl-pyridin-2-yl)-ethoxy]-benzyl}-thiazolidine-2,4-dione

- Marketed in USA in August of 1999

Αlpha – glycosidase inhibitors :Block enzymes that help digest starches slowing the rise in B.G.L.

AGI’s- Precose ® (acarbose),

- Glyset ® (miglitol)

N

OO

OO

O

H

H H

H H

1-(2-Hydroxy-ethyl)-2-hydroxymethyl-piperidine-3,4,5-triol

Meglitinides : Stimulate more insulin production ; dependant upon level of glucose present

Meglitinides- Prandin ® (repaglinide)

- Starlix ® (nateglinide)

O

OHO

NH

N

O

2-Ethoxy-4-{[3-methyl-1-(2-piperidin-1-yl-phenyl)-butylcarbamoyl]-methyl}-benzoic acid

O

OH

NH

O

2-[(4-Isopropyl-cyclohexanecarbonyl)-amino]-3-phenyl-propionic acid

Diabetes – Oral MedicationsSummary

6 Classes :

Sulfonylureas stimulate β cells

Biguanides improves insulin’s ability to move glucose

Sulfonylureas and biguanide combination drugs BOTH

Thiazolidinediones cells more sensitive to insulin

Alpha-glycosidase inhibitors Block enzymes that help digest starches

Meglitinides stimulate β cells (dependant upon glucose conc.)

In Conclusion :

2 major types of diabetes

(3 with Gestational) Type 1 => insulin dependant (5-10%) Type 2 => may treat with oral medication

which may alter insulin production &/or sensitivity ; disease often succumbs to insulin dependence (>90%)