Why body weight of patient is normal in Type 1 Diabetes mellitus
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Why Body Weight Is "Normal" in Type 1 Diabetes Mellitus
This is actually a nuanced point best understood in comparison to Type 2 DM, where obesity is the hallmark. The Guyton & Hall table (Table 79.3) explicitly states:
| Feature | Type 1 DM | Type 2 DM |
|---|---|---|
| Body mass | Low (wasted) to normal | Increased (visceral obesity) |
| Plasma insulin | Low or absent | Normal to high initially |
| Insulin sensitivity | Normal | Reduced |
So the correct clinical picture is: Type 1 DM patients are lean-to-normal weight, NOT obese - which is the contrast being drawn against Type 2.
The Metabolic Reason: Why Type 1 Does NOT Cause Obesity
In Type 1 DM, the pancreatic beta-cells are destroyed (autoimmune), so insulin is absent. Without insulin:
1. No fat storage (no lipogenesis)
- Insulin is the primary anabolic signal for storing fat in adipose tissue.
- Without insulin, lipogenesis is blocked and lipolysis increases - fat is broken down, not stored.
- Free fatty acids are released into circulation and used as fuel.
2. No protein anabolism (muscle wasting)
- Insulin normally drives amino acid uptake into muscle and stimulates protein synthesis.
- Without insulin, protein catabolism increases - muscle and body proteins are broken down to provide gluconeogenic substrates (amino acids → glucose in the liver).
- This leads to muscle wasting and weight loss.
3. Massive glucose losses in urine
- Blood glucose rises to 300-1200 mg/100 mL.
- Once it exceeds the renal threshold (~200 mg/100 mL), glucose spills into the urine.
- In severe uncontrolled Type 1 DM, 100+ grams of glucose can be lost per day - representing a huge caloric loss despite polyphagia (increased eating).
4. Net result: weight loss, not gain
As Guyton & Hall states directly:
"Failure to use glucose for energy leads to increased utilization and decreased storage of proteins and fat. Therefore, a person with severe untreated diabetes mellitus experiences rapid weight loss and asthenia, despite eating large amounts of food (polyphagia)."
- Guyton and Hall Textbook of Medical Physiology, p. 974
Why Does This Differ from Type 2?
In Type 2 DM:
- Insulin is present (even elevated) early in the disease as compensation for insulin resistance.
- This elevated insulin actively promotes fat storage (insulin is a fat-storing hormone).
- Obesity (especially visceral/abdominal) is both a cause and a consequence.
- Hence Type 2 patients typically have increased body mass.
In Type 1 DM:
- There is NO insulin to drive fat or protein storage.
- The body is in a constant catabolic state.
- Body weight is therefore lean to normal - and in untreated cases, actively losing weight.
Summary
The reason Type 1 DM patients are normal or low weight (not obese) is:
- No insulin = no signal for fat or protein storage.
- Increased lipolysis - fat depots are broken down.
- Increased protein catabolism - muscle is wasted for gluconeogenesis.
- Caloric loss through glucosuria - hundreds of grams of energy lost in urine daily.
- Contrast with Type 2 - where high circulating insulin drives obesity, Type 1 has none.
This is why classic teaching distinguishes: Type 1 = young, lean patient with sudden onset; Type 2 = older, obese patient with gradual onset. (Guyton and Hall, Table 79.3)
Name the primary blood clotting factors
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I now have complete, authoritative data from two major textbooks. Here is the full answer:
Blood Clotting Factors (Coagulation Factors)
There are 13 recognized clotting factors (numbered I-XIII; Factor VI does not exist - it was later found to be the same as activated Factor V and was removed from the list). The numbers reflect the order of discovery, not the order in which they act.
| Factor | Common Name(s) |
|---|---|
| Factor I | Fibrinogen |
| Factor II | Prothrombin |
| Factor III | Tissue Factor (Tissue Thromboplastin) |
| Factor IV | Calcium (Ca²⁺) |
| Factor V | Proaccelerin; Labile Factor; Ac-globulin |
| Factor VI | |
| Factor VII | Proconvertin; SPCA (Serum Prothrombin Conversion Accelerator); Stable Factor |
| Factor VIII | Antithrombophilic Factor A (AHF); Antithrombophilic Globulin (AHG) |
| Factor IX | Christmas Factor; Plasma Thromboplastin Component (PTC); Antithrombophilic Factor B |
| Factor X | Stuart-Prower Factor |
| Factor XI | Plasma Thromboplastin Antecedent (PTA); Antithrombophilic Factor C |
| Factor XII | Hageman Factor |
| Factor XIII | Fibrin-Stabilizing Factor (FSF); Fibrinoligase |
Source: Guyton and Hall Textbook of Medical Physiology, Table 37.1; Harper's Illustrated Biochemistry, Table 55-1
Additional Contact Phase Factors
Beyond the numbered factors, two additional proteins are essential to the contact (intrinsic) pathway:
| Factor | Common Name |
|---|---|
| Prekallikrein | Fletcher Factor |
| High-Molecular-Weight Kininogen (HMWK) | Fitzgerald Factor |
Key Points to Remember
- Factor I (Fibrinogen) and Factor II (Prothrombin) are classically referred to by their common names, not numbers.
- Factor III (Tissue Factor) and Factor IV (Calcium) are also rarely called by their numbers in clinical practice.
- Factors II, VII, IX, X are the Vitamin K-dependent factors (along with Protein C and Protein S) - warfarin inhibits all of these.
- Factor VIII deficiency = Hemophilia A; Factor IX deficiency = Hemophilia B (Christmas disease).
- Factor XIII crosslinks fibrin monomers into a stable clot - it is the final step in clot consolidation.
- More than 50 substances affect coagulation in total, but these are the 13 primary numbered factors. (Guyton and Hall, p. 482)
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