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Today, I want to talk to you about Diabetes Mellitus types I, II, and III.
This is a topic I’m deeply passionate about—and one that also overwhelms me. Because diabetes is not simply a matter of “high” or “low” blood sugar. It is much more complex.
We call it the silent killer because most of the time it shows no obvious symptoms. Its progression is so slow and deceptive that by the time the first clinical signs appear, the damage is often already significant.
This is a multisystemic disease: from very early stages, it begins to affect vital organs—brain, heart, kidneys, eyes, and peripheral nerves. And yes, it goes far beyond a lab number.
Diabetes is a multifactorial condition, rooted in genetics but primarily influenced by lifestyle and, especially, eating habits—one of the hardest things to change.
As a trained by experience, and passionate diabetologist, I can tell you that thousands of books have been written on this disease. And yet, the more you study, the more you realize something both humbling and profoundly true:
“The more I know, the more I realize I know nothing.”
What is Diabetes Mellitus?
1. Type I
An autoimmune disease where the immune system destroys pancreatic β-cells, reducing or eliminating insulin production. It often begins in children or young adults.
2. Type II
Progressive insulin deficiency plus peripheral resistance. Strongly linked to obesity and a sedentary lifestyle. It accounts for the vast majority of diabetes cases.
3. Type III (a modern and ambiguous term)
Let me draw your attention here. If you’re taking care of yourself, maintaining a healthy weight, exercising—and your A1C keeps rising—your doctor should consider Diabetes Mellitus Type III. In my experience, this form behaves like Type I in adults and requires insulin treatment.
Type 3c (pancreatogenic): Secondary to chronic pancreatitis, cancer, or pancreatic surgery. It affects both exocrine and endocrine functions.
Type 3 (cerebral): A term proposed to describe insulin resistance in the brain, linked to Alzheimer’s disease. Not officially recognized as a clinical diagnosis—yet.
Who Develops Each Type?
Type I: More common in children and adolescents. Genetic predisposition (autoantibodies). It can be triggered by viral infections.
Type II: More frequent in adults with obesity, hypertension, and dyslipidemia. Caused by both genetic and metabolic factors.
Type 3c: Seen in people with chronic pancreatic disease; represents 5–10% of diabetes cases in the West.
Type 3 cerebral: Associated with insulin resistance, diabetes, and increased risk of Alzheimer’s or vascular dementia.
Comparison Table
Feature Type I Type II Type 3c Type 3 (Cerebral)
Main defect: Absolute insulin loss, Resistance + progressive loss, Pancreatic damage + β-cell loss, Brain insulin resistance
Onset Childhood/adolescence Adults (sometimes younger) When pancreatic disease occurs Older adults with diabetes
Insulin production: Very low or absent. The variable decreases over time. Low after pancreatic injury: Signal disruption in the brain
Autoantibodies Present Not typically present Not present Not applicable
Initial treatment: Insulin (mandatory) Lifestyle → oral meds → insulin Insulin + digestive enzymes Glucose control + research on nasal insulin
Early Symptoms
Common to all types: Excessive thirst, frequent urination, blurred vision, fatigue, weight loss, and infections.
Type I: Sudden onset within weeks; possible ketoacidosis.
Type II: Gradual onset; often asymptomatic early on.
Type 3c: Abdominal pain, steatorrhea, and malabsorption along with typical symptoms.
Type 3 cerebral: Cognitive symptoms resembling Alzheimer’s—memory loss, impaired judgment.
Why A1C and C-Peptide Matter
HbA1c: Reflects 2–3 month average glucose. Each point above normal increases macrovascular risk by ~18%.
C-peptide: Measures insulin production. Low in Type I and 3c; normal/high in Type II. Crucial for distinguishing types and adjusting treatment.
Diagnosis
Lab tests:
Fasting or post-load glucose (>126 mg/dL or >200 mg/dL)
HbA1c ≥6.5% (diagnostic)
Autoantibodies (GAD, IA2) → Type I
C-peptide: low = deficiency, normal/high = resistance
Additional tools:
Genetic testing → MODY
Imaging and symptoms → Type 3c
Neuropsych testing + brain imaging → Type 3 cerebral
Organs Affected and How to Monitor
Heart: ECG, stress test, coronary calcium scan. The risk of heart disease is doubled.
Kidneys: Urine albumin, GFR. Nephropathy may appear after 5–10 years and progress to ESRD.
Eyes: Fundoscopy; leading cause of blindness.
Nerves/Feet: Sensory exam and Doppler. Risk of ulcers and amputations.
Cerebrovascular system: Higher risk of stroke and vascular dementia.
Sexual function: Neuropathy and vasculopathy lead to erectile dysfunction.
Brain (Type 3): Neuroimaging, cognitive tests for Alzheimer’s.
What to Expect from Your Doctor
Annual check: A1C, BP, lipids, kidney function, eye exam, foot exam.
A1C every 3–6 months, depending on control.
C-peptide test if diagnosis is unclear.
Detect subclinical complications: albuminuria, retinopathy.
Risk factor management: statins, BP meds, lifestyle coaching.
Natural Recommendations
High-fiber diet, low in refined sugars and saturated fats.
Exercise ≥150 min/week (walking, swimming, etc.).
Maintain a healthy weight.
Quit smoking and control blood pressure.
Current & Emerging Treatments
Type I: Multiple daily insulin or insulin pump + pramlintide (amylin analog).
Type II: Metformin, sulfonylureas, DPP‑4 inhibitors, GLP‑1 RAs, SGLT2 inhibitors, late insulin. GLP‑1 and SGLT2 have proven cardiovascular and renal benefits.
Type 3c: Insulin + pancreatic enzymes.
Type 3 cerebral: Glucose control + trials on nasal insulin for Alzheimer’s.
GLP‑1, Fatty Liver, and Insulin Resistance
GLP‑1 RAs (e.g., semaglutide, liraglutide):
Lower blood glucose and appetite promote weight loss.
Protective for the heart, kidneys, and possibly the rain.
Reduce hepatic steatosis and insulin resistance (HOMA-IR).
Clinical trials (e.g., NEJM) show NASH resolution in 62–63% and fibrosis improvement in ~33–37% after 72 weeks.
Dual agonists (GLP‑1/GCGR):
Like cotadutide, improves liver function and insulin sensitivity in animal models.
Lower risk of hepatic decompensation in cirrhotic diabetics.
Intranasal Insulin for Brain Resistance
Direct-to-brain insulin (INI) tested for Alzheimer’s.
Meta-analyses show slight cognitive improvement in non-APOE4 carriers.
No long-term clinical benefit has been confirmed yet.
New low-dose devices (≈20 IU) are under evaluation.
Promising, but not yet standard care.
“Type 3 Cerebral” and the Metabolic-Cognitive Link
Up to 50–70% of T2D patients have NAFLD.
Fatty liver fuels insulin resistance and inflammation.
Ideal treatment: glucose control, weight loss, hepatic protection, and cardiovascular care.
GLP‑1 RAs: Metabolic synergy—helping the liver, heart, and potentially the brain.
What to Discuss at Your Next Checkup
1. Liver function (ALT/AST, ultrasound or elastography if overweight).
2. Metabolic status: HbA1c, lipids, HOMA‑IR.
3. Cognitive evaluation if decline is suspected.
4. Ask about GLP‑1 RAs if you have fatty liver + diabetes or obesity.
5. Consider clinical trials (intranasal insulin, dual agonists).
New Treatments in Development
Cotadutide: GLP‑1/GCGR dual agonist—promising in mice.
Pemvidutide: In phase II for MASH; improves steatosis and lipids.
Efruxifermin (FGF21 analog): Improved fibrosis in 39–41% in phase 2b.
INI trials for Alzheimer’s continue based on genotype and dosage.
Final Thoughts
GLP‑1 RAs are now front-line therapy for patients with fatty liver and diabetes/obesity.
Dual agonists (GLP‑1/GCGR or GLP‑1/GIP) represent a new frontier.
Intranasal insulin may offer a window into brain-directed treatment for metabolic disease.
Prognosis
Type I: reduced life expectancy (~10–12 years).
Type II and 3c: vascular complications if uncontrolled.
“Type 3 cerebral”: not an established diagnosis, but treatment may slow cognitive decline.
Final Message
Type I, II, and 3c diabetes each have distinct origins and management strategies.
The emerging concept of “Type 3 cerebral” offers hope for Alzheimer’s prevention.
Accurate diagnosis (A1C, C-peptide, autoantibodies, genetics) and a holistic approach (medications, lifestyle, and organ monitoring) are essential.
New treatments are already improving cardiovascular, renal, and possibly cognitive
RaulAyalaMD
@MyDoctorOnCall.com