Diabetes Mellitus: Pathophysiology, Diagnosis, and Management for Med-Surg

Diabetes Mellitus

A chronic metabolic disorder caused by problems with insulin production, secretion, or use, leading to abnormal carbohydrate, fat, and protein metabolism and resulting in hyperglycemia.

Type 1 Diabetes

Autoimmune destruction of pancreatic beta cells, absolute insulin deficiency.

Type 2 Diabetes

Insulin resistance with relative insulin deficiency.

Prediabetes

Condition where fasting glucose is 100-125 mg/dL or A1C 5.7-6.4%, placing the person at high risk for Type 2 DM.

Classification of Diabetes Mellitus and Glucose Tolerance Levels

Table 46.1 - Diagnostic table that lists the classification of diabetes and related glucose levels.

Pathophysiology of Diabetes Mellitus

Insufficient insulin or poor cellular response prevents glucose entry into cells, causing hyperglycemia and breakdown of fat and protein for energy.

Insulin's Role in Metabolism

Promotes glucose transport into cells, glycogen storage, and inhibits fat/protein breakdown.

Fasting Plasma Glucose (FPG) Value for Diabetes

≥ 126 mg/dL on two occasions confirms diabetes.

Random Plasma Glucose Level for Diabetes

≥ 200 mg/dL with classic symptoms (polyuria, polydipsia, polyphagia) confirms diabetes in a symptomatic patient.

2-Hour Oral Glucose Tolerance Test (OGTT) Diagnostic Threshold

≥ 200 mg/dL 2 hours after consuming 75 g glucose.

Normal HbA1C and Diabetes Indicator

Normal < 5.7%; ≥ 6.5% = diabetes.

Risk Factors for Hypoglycemia in Older Adults

Decreased renal function, polypharmacy, delayed appetite cues, and impaired counter-regulatory response.

Teaching Priorities for Geriatric Patients with Diabetes

Simplify regimens, stress hydration, avoid skipping meals, and monitor for confusion or dizziness as hypoglycemia signs.

Lifestyle Modifications to Prevent Type 2 Diabetes

Weight loss, balanced diet, 150 min/week exercise, smoking cessation, and blood-pressure/lipid control.

3 Ps of Diabetes

Polyuria, polydipsia, polyphagia.

Early Signs of Hypoglycemia

Sweating, shakiness, hunger, irritability, anxiety.

Late or Severe Symptoms of Hypoglycemia

Confusion, seizures, loss of consciousness.

Manifestations Suggesting Hyperglycemia

Dry mouth, blurred vision, fatigue, frequent urination, weight loss.

Primary Goal of Medical Nutrition Therapy (MNT) for Diabetes

Achieve normal glucose, lipid, and BP levels through balanced intake and consistent carbohydrate counting.

Sick-Day Rules for Diabetic Clients

Continue insulin, monitor glucose q4h, stay hydrated, and notify provider if glucose > 250 mg/dL or ketones present.

Alcohol Consumption for Diabetic Patients

Alcohol should be limited for diabetic patients.

Gluconeogenesis inhibition

It inhibits gluconeogenesis and can cause delayed hypoglycemia, especially when taken on an empty stomach.

Recommended alcohol intake for diabetes

1 drink/day (women) or 2 drinks/day (men), with food.

Effect of exercise on blood glucose

Lowers glucose by increasing cellular uptake; improves insulin sensitivity.

Precautions before exercising for diabetic clients

Check glucose; eat a 15 g carbohydrate snack if < 100 mg/dL; avoid exercise if > 250 mg/dL and ketones present.

Importance of SMBG

Enables early detection of hypo/hyperglycemia and guides medication or diet adjustments.

Frequency of SMBG for insulin patients

At least before meals and bedtime; more often during illness or medication change.

Rapid-acting insulin characteristics

15 min onset, 3-5 hr duration.

Short-acting insulin characteristics

30 min onset, 5-8 hr duration.

Intermediate insulin characteristics

NPH, 1-2 hr onset, 12-18 hr duration.

Long-acting insulin characteristics

Glargine, 24 hr duration, no peak.

Dawn Phenomenon

Early-morning hyperglycemia from overnight GH release; managed by adjusting insulin timing.

Somogyi effect

Rebound hyperglycemia after nighttime hypoglycemia; check 3 a.m. glucose to differentiate.

Examples of oral antidiabetic agents

Metformin ↓ hepatic glucose; Sulfonylureas stimulate insulin release; DPP-4 inhibitors prolong GLP-1 action.

Type of syringe for insulin

Insulin syringe calibrated in units (typically 100 U/mL).

Insulins that can be mixed

Regular and NPH only; clear before cloudy.

Common insulin injection sites

Abdomen (best absorption), arms, thighs, buttocks; rotate within one region.

Hallmark features of DKA

Ketonuria, fruity breath, Kussmaul respirations, metabolic acidosis, dehydration.

Nursing priorities in DKA

IV fluids (0.9% NS → D5 ½NS), regular insulin drip, electrolyte monitoring (K+).

Distinguishing HHS from DKA

HHS = no ketones, glucose > 600 mg/dL, extreme dehydration, often in Type 2 elderly patients.

Microvascular complications of diabetes

Damage to small vessels → retinopathy, nephropathy, neuropathy.

Macrovascular complications of diabetes

Damage to large arteries → CAD, CVA, PVD.

Annual screenings to prevent long-term complications

Eye exam, urine microalbumin, foot inspection, lipid and BP checks.

Key nursing priorities for diabetic patients in hospital

Monitor glucose regularly, coordinate insulin with meals, educate on hypoglycemia signs, ensure hydration.

Discharge-teaching points for diabetic self-management

Medication timing, diet planning, exercise rules, sick-day protocol, foot care, and when to contact provider.