fix(la): Delta calculation mmoll

Trio/Sources/Services/LiveActivity/LiveActivityAttributes+Helper.swift

@@ -39,20 +39,25 @@ extension LiveActivityAttributes.ContentState {
 
     static func calculateChange(chart: [GlucoseData], units: GlucoseUnits) -> String {
         guard chart.count > 2 else { return "" }
-        let lastGlucose = chart.first?.glucose ?? 0
-        let secondLastGlucose = chart.dropFirst().first?.glucose ?? 0
-        let delta = lastGlucose - secondLastGlucose
-        let deltaAsDecimal = units == .mmolL ? Decimal(delta).asMmolL : Decimal(delta)
+
         let formatter = NumberFormatter()
         formatter.numberStyle = .decimal
         formatter.maximumFractionDigits = 1
+        formatter.positivePrefix = "  +"
+        formatter.negativePrefix = "  -"
+
+        var lastGlucose = Decimal(chart.first?.glucose ?? 0)
+        var secondLastGlucose = Decimal(chart.dropFirst().first?.glucose ?? 0)
         if units == .mmolL {
+            lastGlucose = lastGlucose.asMmolL
+            secondLastGlucose = secondLastGlucose.asMmolL
+
             formatter.minimumFractionDigits = 1
             formatter.maximumFractionDigits = 1
         }
-        formatter.positivePrefix = "  +"
-        formatter.negativePrefix = "  -"
-        return formatter.string(from: deltaAsDecimal as NSNumber) ?? "--"
+        
+        let delta = lastGlucose - secondLastGlucose
+        return formatter.string(from: delta as NSNumber) ?? "--"
     }
 
     init(