ENDOCRINOLOGY

• Glucose is an essential energy source for red blood cells and nerve cells, with nerves using ketones during starvation.

Glucose Regulation

• Insulin lowers blood glucose levels, leading to a hypoglycemic effect.
• Glucagon, cortisol, catecholamines, and growth hormones all increase blood glucose levels, resulting in a hyperglycemic effect.
• After a meal, glucose is stored as glycogen in the liver and fat tissues.
• During fasting, glucose is retrieved through glycogenolysis in the liver and gluconeogenesis from amino acids.

Insulin's Role

• Insulin, a polypeptide hormone from beta cells in the Islets of Langerhans, is released in response to hyperglycemia.
• Proinsulin is broken down into insulin and C-peptide, facilitating glucose absorption into cells and promoting fat and protein synthesis.

Glucose Control Functions

• Glucose control maintains blood sugar levels, stores energy, and provides energy when needed.
• The brain can absorb glucose from the blood independently of insulin control but is vulnerable to conditions altering blood sugar levels.

Hyperglycemic Promoters

• Key hyperglycemic promoters include glucagon, catecholamines, cortisol, and growth hormone.
• Glucagon, produced by alpha cells in the Islets of Langerhans, is released when glucose levels are low, opposing insulin's actions.
• Catecholamines, secreted by the adrenal medulla during stress, raise blood glucose levels to fuel the fight or flight response.
• Cortisol and growth hormone both promote gluconeogenesis, increasing glucose levels.

Hyperglycemia

• Hyperglycemia typically arises from an imbalance of glucose, uncontrolled homeostatic hormones, or excess cortisol and catecholamines and also fast glucose IV drips can cause this

Diabetes Mellitus

• Diabetes mellitus is a group of conditions marked by chronic hyperglycemia due to insulin deficiency, tissue resistance, or both.
• Insulin's role is to convert excess blood glucose into glycogen for storage.
• Primary diabetes mellitus is insulin-dependent (Type 1), indicating hormone failure (insulin).
• Secondary diabetes mellitus can result from pancreatitis, pancreatectomy, Cushing's disease, acromegaly, or drugs like steroids and thiazide diuretics.
• Insulin-independent diabetes mellitus is usually in older patients (Type 2), where insulin is produced, but tissues are resistant to its effects.

Type 1 vs Type 2 Diabetes

• Epidemiology:
  • Type 1 affects younger patients (10-20 years), while Type 2 affects older patients (over 40 years).
• Onset:
  • Type 1 has an acute onset, whereas Type 2 has a chronic onset.
• Habitus:
  • Type 1 patients are typically lean, while Type 2 patients are often obese.
• Ethnicity:
  • Type 1 is more common in European descent, while Type 2 affects all racial groups.
• Family History:
  • Type 1 is uncommon in family history, compared to Type 2, which is frequent.
• HLA System:
  • Type 1 patients often have DR3/DR4, while Type 2 has no HLA links.
• Risk to Identical Twin:
  • Type 1 has a 30-35% risk, whereas Type 2 has over a 90% risk.
• Etiology:
  • Type 1 is autoimmune/viral, while Type 2 is related to obesity.
• Clinical:
  • Type 1 always requires insulin, while Type 2 can be managed with diet/oral hypoglycemics and occasionally needs insulin.

Development of Diabetes

• Type 1 diabetes results from viral infection in HLA DR3/DR4 individuals, generating auto-antibodies that lead to autoimmune destruction of insulin-producing pancreatic B cells.
• Type 2 diabetes involves a 50% reduction in beta cell mass, causing hyperglycemia due to inadequate insulin secretion and insulin resistance in peripheral tissues.

Long-Term Complications of Diabetes Mellitus

• Neurological conditions and diabetic ketoacidosis.
• Autonomic symptoms (palpitations, sweats).
• Oral candidiasis.
• Increased risk of MI/stroke/kidney failure/retinal loss of vision/increased risk of infection/salivary gland dysfunctional flow/BMS/lichen planus/more active caries/traumatic ulcers.

Hyperglycemia Symptoms

• Excess blood glucose exceeds the renal re-absorption limit, leading to increased urinary frequency.
• Sugar in the renal filtrate acts as an osmotic water carrier into urinary outflow.

Diet Adjustments

• Adjustments include reducing fat to 30-35% of total energy intake (mainly unsaturated), protein to 10-15%, and carbohydrate to 50% (complex carbohydrates).

Oral Hypoglycemics

• Oral hypoglycemics are recommended if diet control alone is insufficient.
  • Suphonylureas: Increase beta cell insulin secretion and reduce peripheral resistance to insulin action.
    • Glibenclamide: Long-acting and renal excretion, avoid in elderly and patients renal failure.
    • Tolbutamide: Short-acting and liver metabolism, better for older and patients with renal failure.
  • Biguanides: Metformin decreases gut glucose absorption and increases peripheral tissue insulin sensitivity. It is good for obese people, but side effects include diarrhea, anorexia, and lactic acidosis.

Impact on Life Expectancy

• Poorer control and earlier onset reduce life expectancy, primarily due to diabetic nephropathy.

Macrovascular Complications

• Accelerated atheroma: Additive with other large vessel disease risk factors (hypertension, hyperlipidemia, and smoking).
• Stroke, ischemic heart disease/MI, ischemic limbs/gangrene can also occur.

Microvascular Diseases

• Diabetic retinopathy- blindness can be present
• Diabetic nephropathy- renal failure (glomerulosclerosis and proteinuria) can arise
• Diabetic neuropathy- irreversible glove and stocking loss of peripheral sensation and autonomic systemic failures e.g. impotence, loss of joint and position sense mainly affects fingers and feet, and some mononeuropathies can be prevalent

Avoiding Complications

• Meticulous glycemic control and urine testing for early signs of albuminuria can help delay and avoid complications.

Dental Infections

• Diabetes affects wound healing in the oral cavity and extraction socket healing.
• Oral candidiasis can develop more easily.

Skin Infections

• Poorly controlled diabetes reduces polymorph function, increasing the risk of UTI and skin infections.
  • Lipodermatosclerosis = fatty lumps at repeatedly over used injection sites.
  • Necrobiosis liopoidica diabeticorum = red/waxy brown deposits on shins.
  • Granuloma annulare = fleshy nodules over extensor surfaces of fingers.

Diabetes Issues in Dentistry

• Try to avoid hypoglycemia
• Predisposition to infection
• More severe periodontal disease
• Oral candidosis if uncontrolled can lead to angular stomatitis
• Peripheral autonomic neuropathy may cause paraesthesia in the mouth and salivary gland swelling as well as orthostatic hypotension
• Burning mouth sensation
• Dry mouth – dehydration due to polyuria Drugs
• Steroids increase blood glucose
• Some antibiotic –tetracycline enhance insulin action
• NSAIDs should be used with caution due to renal failure and risk of GI bleed

Diabetic Control Procedures

• Smooth diabetic control minimizes the risk of hypo/hyperglycemia and infections provide best control/balance to starvation and the body’s catabolic response to surgery.
• Type 1 / IDDM Diabetes patients:
• Are put as 1st on the operation list i.e. early morning.
• Convert long to short acting insulins 1-2 days beforehand.
• 5% dextrose/insulin/K infusions or as a sliding scale (sugar in one arm, insulin in the other arm) to gain control over the patients diabetic state until they are able to eat again.
• Type 2 / NIDDM Diabetes patients:
• Convert long to short acting drugs prior to theatre date as these are easier for balancing.
• Consider IV regimes if “brittle” (difficult control) or procedure long of won’t allow early post operative feeding.

Dental Implications

• Periodontal disease, xerostomia, and the risk of ischemic heart disease.

Insulin

• Insulins are used as injectables as a small protein, as a larger amount won’t withstand gastric acid transit.
  • Actrapid: Fast-acting pure - onset 15-60 minutes, duration 4-6 hours. Uses in multi injection regimes, surgery and A&E.
  • Monotard, insultard: Intermediate acting ≈ 12-24 hours and Long acting ≈ over 24 hours.
  • Mixtard: Mixture of long and short acting often used in bd regimes to have smooth effects.
• Insulins have different speeds of action to ensure blood glucose levels are adequate without excess, reducing the risk of hypoglycemia.

Measuring Blood Glucose Levels

• Fingerprick glucose: Read by test strips or digital readout glucometer (BM stix).
• Urine dipstix: Crude as glucose only appears in urine if BM exceeds the renal threshold for the individual (type 7-13mmol/l) useful for elderly, people with Parkinson’s, dementia.
• Lab serum glucose: Part of biochem test, most accurate test which gives accurate level at the time of tests only. Takes time return
• HbA1C: Glycosylated Hb measures how much Hb has sugar molecules on it (norm = 4-6%) helpful for monitoring long term controls and is a trend manager.

Acute Hypoglycemia

• Sugar flow in is too low for the amount of insulin around, overwhelmed by relative insulin.