What initial investigations should be done in a newly diagnosed type 2 diabetes mellitus (T2DM) case?

Initial Investigations for Newly Diagnosed Type 2 Diabetes in a 32-Year-Old Female

All newly diagnosed type 2 diabetes patients require immediate comprehensive screening for microvascular and macrovascular complications, as complications may already be present at diagnosis, particularly in younger adults where the disease onset often precedes clinical recognition by several years.

Immediate Laboratory Investigations

Glycemic Assessment

• HbA1c measurement to establish baseline glycemic control and confirm diagnosis if not already done (≥6.5% diagnostic) 1, 2
• Fasting plasma glucose if HbA1c was not the initial diagnostic test 1

Renal Function Screening (Critical at Diagnosis)

• Urine albumin-to-creatinine ratio (UACR) in a random spot collection—this is the preferred method over 24-hour collections 3
• Serum creatinine with calculated eGFR to assess kidney function and stage any chronic kidney disease 3, 1
• Serum potassium as baseline, particularly important before initiating certain medications 3
• Two of three specimens should be abnormal over 3-6 months to confirm persistent albuminuria, though initial screening starts immediately 3

Critical caveat: Exercise within 24 hours, infection, fever, marked hyperglycemia, marked hypertension, and menstruation can falsely elevate albumin excretion 3. If microalbuminuria is detected, obtain a first morning void to exclude benign orthostatic proteinuria, which is common in young adults and requires no treatment 3.

Cardiovascular Risk Assessment

• Complete lipid profile: LDL cholesterol, HDL cholesterol, total cholesterol, and triglycerides 1, 2
• Blood pressure measurement to assess for hypertension 1
• These determine need for statin therapy and cardiovascular risk stratification 1

Immediate Specialist Referrals

Ophthalmologic Examination (Non-Negotiable)

Dilated comprehensive eye examination by an ophthalmologist or optometrist must be performed shortly after diagnosis—not delayed 3, 1. This is fundamentally different from type 1 diabetes, where screening can wait 5 years.

The examination must include 3:

• Visual acuity testing
• Slit-lamp biomicroscopy
• Intraocular pressure measurement
• Gonioscopy if neovascularization suspected or IOP elevated
• Stereoscopic examination of the posterior pole
• Peripheral retinal examination via indirect ophthalmoscopy

Rationale: Up to 30% of type 2 diabetes patients have retinopathy at diagnosis, and 3% already have clinically significant macular edema or high-risk features requiring immediate intervention 3. The disease onset often precedes diagnosis by years, particularly in younger adults who may not have routine screening 3.

Additional Essential Screening

Neuropathy Assessment

• Comprehensive foot examination including inspection, assessment of foot pulses, and testing for loss of protective sensation using at least one of: 10-g monofilament, vibration testing with 128-Hz tuning fork, pinprick sensation, ankle reflexes, or vibration perception threshold 1
• Screening for distal symmetric polyneuropathy should begin at diagnosis in type 2 diabetes 1

Hepatic Function

• Liver function tests (ALT, AST) as baseline before initiating metformin or other medications 2

Special Considerations for a 32-Year-Old Patient

Rule Out Atypical Diabetes

Given the young age (under 35 years), consider antibody testing to distinguish type 1 from type 2 diabetes if there is any phenotypic overlap 4:

• GAD (glutamic acid decarboxylase) antibodies as the primary test 4
• If GAD negative and clinical uncertainty persists, test IA-2 and ZnT8 antibodies 4
• C-peptide testing (random, non-fasting within 5 hours of eating) if already on insulin or if classification remains uncertain after antibody testing 4

Red flags suggesting type 1 or atypical diabetes: BMI <25 kg/m², unintentional weight loss, ketoacidosis or ketosis at presentation, rapid progression to insulin dependence, family history of autoimmunity 4.

Reproductive Considerations

• Pregnancy planning counseling is essential for a 32-year-old female, as pre-existing diabetes requires comprehensive eye examination before conception and close monitoring throughout pregnancy 3
• Discuss teratogenic risks of certain medications and need for optimal glycemic control before conception 3

Monitoring Schedule After Initial Workup

• Annual screening: UACR, serum creatinine/eGFR, comprehensive eye examination (if initial exam normal, can extend to every 2 years), foot examination, lipid profile 3, 1
• More frequent monitoring if abnormalities detected: eGFR every 3-6 months if stage 3-4 CKD, eye exams every 3-12 months if retinopathy present 3

Common Pitfalls to Avoid

• Do not delay ophthalmologic examination assuming the patient is "too young" for complications—younger onset type 2 diabetes is often more aggressive 3
• Do not assume type 2 diabetes based solely on age and obesity—antibody testing is warranted if any atypical features present 4
• Do not diagnose persistent microalbuminuria on a single specimen—confirm with 2 of 3 abnormal collections, and exclude transient causes 3
• Do not forget to assess for orthostatic proteinuria in young adults with microalbuminuria by obtaining first morning void 3