High SHBG in Type 1 Diabetes: Causes and Management
Direct Answer
Your elevated SHBG of 90 nmol/L is paradoxically high for Type 1 diabetes and contradicts the typical pattern—most research shows Type 1 diabetics actually have LOW SHBG levels, not high ones. 1, 2, 3
Understanding the Paradox
What Research Shows About SHBG in Type 1 Diabetes
- Type 1 diabetics typically have DECREASED SHBG levels, not elevated ones, particularly in young females where SHBG is inversely influenced by insulin dose, BMI, and HbA1c 1
- Male children and young adults with Type 1 diabetes show HIGHER SHBG and total testosterone compared to non-diabetic siblings, which appears related to the absence of endogenous insulin production (C-peptide negative status) 2
- Young women with Type 1 diabetes demonstrate lower SHBG concentrations (61 ± 17 nmol/L) compared to healthy controls (83 ± 18.1 nmol/L), contributing to increased androgen bioavailability 3
Why Your SHBG Might Be High
Since your SHBG is elevated rather than low, consider these alternative explanations:
Non-diabetes factors that INCREASE SHBG:
- Hyperthyroidism or excessive thyroid hormone replacement - thyroid hormones are major regulators of hepatic SHBG production 4
- Liver disease - certain hepatic conditions can paradoxically increase SHBG 4
- Low body weight or eating disorders - reduced caloric intake increases SHBG
- Medications - anticonvulsants, estrogen-containing medications
- Genetic factors - the rs1799941 SNP on the SHBG gene can increase both SHBG (24.7% higher) and total testosterone (14.7% higher) 5
What You Should Do
Immediate Diagnostic Steps
Check thyroid function tests (TSH, free T4) - hyperthyroidism is a common cause of elevated SHBG and occurs more frequently in Type 1 diabetics 4
Assess your diabetes control:
Evaluate liver function - obtain comprehensive hepatic panel (AST, ALT, alkaline phosphatase, bilirubin) to rule out hepatic causes 4
Review all medications - certain drugs can elevate SHBG independent of diabetes status
Management Strategy
If thyroid dysfunction is identified:
- Adjust thyroid medication dosing to achieve euthyroid state
- Recheck SHBG after 3 months of stable thyroid function
If diabetes control is suboptimal:
- Target HbA1c between 7.0-7.5% (53-58 mmol/mol), which represents the lowest risk zone for complications while minimizing hypoglycemia 6
- Optimize insulin regimen using basal-bolus approach with insulin analogs (rapid-acting analogs reduce hypoglycemia by 20% and nocturnal hypoglycemia by 45%) 6
- Consider continuous glucose monitoring (CGM) if not already using, as it reduces hypoglycemia duration by 38% with threshold-suspend features 6
If no clear cause is identified:
- Your elevated SHBG may represent genetic variation (rs1799941 polymorphism) rather than pathology 5
- Monitor for symptoms rather than treating the number alone
- Recheck SHBG in 6 months to assess stability
Clinical Significance
The key question is whether your high SHBG is causing symptoms:
- In males: reduced free testosterone leading to low libido, erectile dysfunction, fatigue
- In females: altered menstrual patterns, though this is less common with HIGH SHBG
Important caveat: The genetic study showed that despite significant associations between the SHBG gene SNP and both SHBG and testosterone levels, there was NO significant association with myocardial infarction, Type 2 diabetes, cancer, or mortality, suggesting that SHBG levels may be a marker rather than a causal factor for metabolic disease 5
Bottom Line
Your high SHBG is NOT a typical consequence of Type 1 diabetes—in fact, it's the opposite of what's expected. 1, 2, 3 Focus your investigation on thyroid function, overall diabetes control, liver health, and medication effects. The elevation likely represents a separate process unrelated to your diabetes, and identifying the underlying cause will guide appropriate management.