Carbohydrate Ratio Adjustment with Soliqua
Do not adjust or give carbohydrate ratios for Soliqua—this fixed-ratio combination does not require carb counting because the lixisenatide component is not dosed based on carbohydrate intake.
Understanding Soliqua's Mechanism
Soliqua (iGlarLixi) combines insulin glargine 100 U/mL with lixisenatide, a GLP-1 receptor agonist, in a fixed ratio 1, 2. The insulin glargine component provides basal insulin coverage targeting fasting glycemia, while lixisenatide primarily addresses postprandial hyperglycemia through multiple mechanisms 1, 3:
- Lixisenatide slows gastric emptying after meals, which reduces postprandial glucose excursions without requiring carbohydrate-based dosing 3
- The GLP-1 component stimulates glucose-dependent insulin secretion and reduces glucagon levels, particularly after the first meal 3, 4
- These effects are complementary to basal insulin, with lixisenatide handling meal-related glucose while glargine manages fasting levels 1, 3
Why Carb Ratios Don't Apply
Carbohydrate-to-insulin ratios are only relevant for prandial (mealtime) rapid-acting insulin, such as insulin aspart, lispro, or glulisine 5. The American Diabetes Association recommends that individuals using rapid-acting insulin by injection or pump should adjust meal and snack insulin doses based on carbohydrate content 5.
However, Soliqua functions differently:
- The lixisenatide component is not titrated based on carbohydrate intake—it's dosed as part of the fixed-ratio combination 1, 2
- Soliqua is titrated based on fasting plasma glucose, not meal composition, with dose adjustments every 3 days until fasting glucose reaches 80-130 mg/dL 6
- The maximum lixisenatide dose is 20 µg/day, achieved through the fixed-ratio titration, regardless of carbohydrate consumption 1
Appropriate Dosing Strategy for Soliqua
Titrate Soliqua based on fasting glucose values, not carbohydrate intake 6:
- Increase by 2-4 units every 3 days until fasting plasma glucose reaches 80-130 mg/dL 6
- The two available pen formulations allow titration of glargine up to 40 IU/day or 60 IU/day, with lixisenatide automatically uptitrated to maximum 20 µg/day 1
- Continue metformin unless contraindicated when using Soliqua 6
When Prandial Insulin and Carb Ratios Become Necessary
If postprandial glucose remains elevated despite optimized Soliqua dosing, consider adding separate rapid-acting prandial insulin 6:
- Start with 4 units of rapid-acting insulin before the largest meal, or use 10% of the basal insulin dose 6
- Only at this point would carbohydrate-to-insulin ratios become relevant, as you would now be using separate prandial insulin that requires carb counting 5
- The typical carbohydrate-to-insulin ratio is calculated as 500/TDD (total daily dose) or individualized based on response 6
Critical Threshold Considerations
When the insulin glargine component of Soliqua exceeds 0.5 units/kg/day and glycemic targets remain unmet, adding separate prandial insulin becomes more appropriate than continuing to escalate Soliqua alone 6. This represents "overbasalization" and signals the need for dedicated mealtime coverage with rapid-acting insulin 6.
Common Pitfall to Avoid
Do not attempt to calculate carbohydrate ratios for the lixisenatide component of Soliqua—this medication is not designed for carbohydrate-based dosing and functions through gastric emptying delay and glucose-dependent mechanisms rather than direct carbohydrate coverage 1, 3.